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COMPARATIVE EVALUATION OF DIFFERENT
METHODS OF MANAGEMENT OF
DYSTOCIA IN DOGS
NARASIMHA MURTHY
DEPARTMENT OF VETRINARY, GYNAECOLOGY AND OBSTETRICS
VETERINARY COLLEGE, HEBBAL, BANGALORE KARNATAKA VETERINARY, ANIMAL AND FISHERIES
SCIENCES UNIVERSITY, BIDAR- 585 401 APRIL, 2011
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COMPARATIVE EVALUATION OF DIFFERENT
METHODS OF MANAGEMENT OF
DYSTOCIA IN DOGS
Thesis submitted to the
Karnataka Veterinary, Animal and Fisheries Sciences University, Bidar
in partial fulfillment of the requirements
For the award of the Degree of
Doctor of Philosophy IN
VETERINARY GYNAECOLOGY AND OBSTETRICS
By
NARASIMHA MURTHY
DEPARTMENT OF VETRINARY, GYNAECOLOGY AND OBSTETRICS
VETERINARY COLLEGE, HEBBAL, BANGALORE KARNATAKA VETERINARY, ANIMAL AND FISHERIES
SCIENCES UNIVERSITY, BIDAR- 585 401 APRIL, 2011
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KARNATAKA VETERINARY, ANIMAL AND FISHERIES SCIENCES UNIVERSITY, BIDAR
DEPARTMENT OF VETERINARY, GYNAECOLOGY AND OBSTETRICS
VETERINARY COLLEGE, HEBBAL, BANGALORE Certificate
This is to certify that the thesis entitled “Comparative evaluation of different methods of management of dystocia in dogs” submitted by Dr. Narasimha Murthy, ID No. DVHK 606 in partial fulfillment of the requirements for the award of Doctor of Philosophy in Animal Reproduction, Gynaecology and Obstetrics of the Karnataka Veterinary, Animal and Fishers Sciences University, Bidar is a record of bonafide research work carried out by him during the period of his study in this University under my guidance and supervision. And the thesis has not previously formed the basis for the award of any degree, diploma, associateship, fellowship or other similar titles.
Bangalore Dr. M. Devaraj April, 2011 Major Advisor
Approved by :
Chairman : ______________________ (M. Devaraj)
Nominated External Examiner : ______________________
Members : 1. ______________________ (A. Krishnaswamy)
2. ______________________ (T.G. Honnappa)
3. ______________________ (K. Jayakumar)
4. ______________________ (L. Ranganath)
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Affectionately dedicated to,
……………My beloved teachers
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ACKNOWLEDGEMENT
“Gratitude is when memory is stored in the heart and not in the mind”.
The success of any venture is depends upon the people who helped in its formation. I take this opportunity to thank the number of people who helped me in this work.
Primarily my mentors Dr. M. Devaraj, Dean, Veterinary College, Gadag and Dr. A. Krishna Swamy Professor and Head, Department of Animal Reproduction, Gynaecology and Obstetrics, Veterinary College, Bangalore the true back bone of this work, who guided me from the very planning of this research, timely advice, constant encouragement and inspiring moral support during all the stages of this study, should be thanked.
I am equally greatfull to my advisory committee members, Dr. Honnappa, T.G, Associate Professor, Department of Animal Reproduction, Gynaecology and Obstetrics, Dr. K. Jayakumar, Professor and Head, Department of Pharmacology and Toxicology, Veterinary College, Bangalore, Dr. L. Ranganath, Professor and Head, Department of Surgery and Radiology, Veterinary College, Bangalore for their valuable suggestions and encouragement throughout the period of study.
My special and Heartful thanks to Dr. V. Chandrashekara Murthy, Assistant Professor, Department of Animal Reproduction, Gynaecology and Obstetrics and Dr. Sudha, G., Assistant Professor, Department of Animal Reproduction, Gynaecology and Obstetrics, Veterinary College, Bangalore, and Dr. M.K. Syeed for their valuable suggestions and encouragement throughout the period of study.
My sincere and special thanks are extended to Dr. Bijurkar, R.G., Assistant Professor, Department of Animal Reproduction, Gynaecology and Obstetrics, Veterinary College, Bidar for his constant inspiration, moral support throughout the course.
I extended my heart full thanks to Dr. Renukaradhya, G.J., my fellow colleague, Department of Animal Reproduction, Gynaecology and Obstetrics, for his kind co operation and suggestions during the period of study.
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My special and unforgatable thanks go to the departmental PG/Ph.D scholars Shankaregowda.A.J, Bijurkar, Bhaghirathi Pugashetti, Kiren Menon, Shilpa, Mahesh, Krisnappa.B, Manjunath, Sharathraj, Dr.Chetan, Adity, Kavyashree, Babu, Vinodh, Anand Patil, Stanzin, Murthy C.N.A and my junior colleagues Drs. Ashwartha, Dost, Hakim, Kavya, Navya and Vibha who were always there with their cordial help and cooperation.
All the non teaching staff members Ganganna (Tumkur), Puttarangappa (Saroooo), Siddharama, Rajanna, Satish, Vijayalakshmi, Thammaiah and Gajalakshmi Bai of the Department of Animal Reproduction, Gynaecology and Obstetrics, for their co operation and making my stay memorable during the period of study.
It is my privilege to extend sincere thanks to my friends Saiprakash (Gili rama), Devaraj (Kavimanase), Chamraju (Egg fried rice), A.K.Santhosh, Kumar Wodeyar, Vishal.B.N, Venkatagiri, Santhosh.H.T, Anirudh Ajjampur, Sridevu, Chetan for their cordial help and co-operation during my stay in the campus.
I should Thank Santhosh.R, Shalini and Bala sir, for their moral support during my stay in the campus and my special thanks go to Dr. Ningappa and Dr. Walmiki, Veterinary College, Bidar for their support during the period of study.
Finally, without the encouragement and support provided by my family members, Kitty sir’s family and Sheenappa Gowda’s family it would have not possible to reach my goal. To all, I am most greatful.
In this recounts I may have not thanked certain people. This does not mean that I am ungrateful to them; it just means that I have a lousy memory.
Bangalore (Narasimha Murthy)
April, 2011
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CONTENTS
Sl. No. Title Page No.
1 INTRODUCTION 1
2 REVIEW OF LITERATURE 4
3 MATERIALS AND METHODS 51
4 RESULTS 64
5 DISCUSSION 99
6 SUMMARY 128
7 BIBLIOGRAPHY 134
8 ABSTRACT 150
9 ANNEXURE 151
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LIST OF TABLES
Table No. Title Page
No.
1 Breedwise distribution of canine dystocia cases treated 66
2 Size wise distribution of canine dystocia cases treated 66
3 Age wise distribution of canine dystocia cases treated 67
4 Parity wise distribution of canine dystocia cases treated 67
5 Behavioral signs observed by owners in bitches with dystocia 69
6 Interval from onset of labour to referral in different types of dystocia 71
7 Mean temperature, heart, pulse and respiration rates in bitches with dystocias 73
8 Nature of vaginal discharges in bitches with dystocia 73
9 Incidence of maternal and fetal dystocia 73
10 Incidence of different maternal dystocias in bitches 74
11 Incidence of maternal dystocias in different age groups of bitch 76
12 Incidence of maternal dystocia in different size bitches 76
13 Incidence of maternal dystocia in different parity bitches 78
14 Incidence of different fetal dystocias in bitches 78
15 Efficacy of medical treatment for relieving dystocia in bitch 80
16 Efficacy of vaginal manipulative procedures for relieving dystocia in bitches 80
17 Indications for cesarean section in bitches 82
18 Mean (±SE) Changes in rectal temperature (OF) of bitches subjected to cesarean section under different anaesthetic protocols and epidural analgesia
84
19 Mean (±SE) changes in heart rate (number per minute) of bitches subjected to cesarean section under different anesthetic protocols and epidural analgesia
84
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Table No. Title Page
No.
20 Mean (±SE) changes in pulse rate (number per minute) of bitches subjected to cesarean section under different anaesthetic protocols and epidural analgesia
84
21 Mean (±SE) changes in respiratory rate (number per minute) of bitches subjected to cesarean section under different anaesthetic protocols and epidural analgesia
86
22 Changes in mean ±SE haemoglobin concentration in bitches subjected to cesarean section under different anaesthetic protocols and epidural analgesia
86
23 Changes in mean ±SE total leucocyte count in bitches subjected to cesarean section under different anaesthetic protocols and epidural analgesia
88
24 Changes in mean ± SE platelet count in bitches subjected to cesarean section under different anaesthetic protocols and epidural analgesia 88
25 Changes in mean±SE Serum ALT in bitches subjected to cesarean section under different anaesthetic protocols and epidural analgesia 90
26 Changes in mean ± SE Serum BUN in bitches subjected to cesarean section under different anaesthetic protocols and epidural analgesia 90
27 Changes in mean ±SE Serum Creatinine in bitches subjected to cesarean section under different anesthetic protocols and epidural analgesia 92
28 Changes in mean ± SE Serum calcium in bitches subjected to cesarean section under different anesthetic protocols and epidural analgesia 92
29 Changes in mean ± SE Random Blood Glucose in bitches subjected to cesarean section with different anesthetic protocols and epidural analgesia
94
30 Evaluation of different anesthetic protocols, epidural analgesia for cesarean section in bitches 96
31 Puppy survivable rate of bitches subjected to caesarean section under different anaesthetic protocols and epidural analgesia 98
Introduction
I. INTRODUCTION
In recent years, advances in canine reproduction have facilitated pregnancy
management to emerge as an important clinical service that has application from the
beginning to the end of gestation. The advances provide new and improved methods of
pregnancy detection; improved use of ultrasound to determine gestational age, assess
fetal wellbeing, predict the date of whelping, detect animals prone for dystocias and
formulate treatment protocols to reduce maternal and fetal mortality (Concannon and
Verstegen, 1998).
Over the last two decades, there has been a tremendous increase in the number of
pedigreed dogs, particularly in the urban areas with the kennel owners even importing
fancy breeds, at an exhorbitant price. The kennel owners have become increasingly aware
of the importance of pre-breeding evaluation of the bitch, availability of the techniques to
determine the exact time of mating, early pregnancy diagnosis and regular monitoring of
the general health of the pregnant animals by the Veterinarian.
The act of parturition perhaps is the most anxious time for the dog breeders, as the
puppy survival rate and the future reproduction of the dam are influenced by events at
this stage. In a study by Forsberg and Forsberg (1989), the frequency of puppy deaths
upto three weeks of age following normal parturition was reported to be 11.9 per cent. In
comparison, the frequency of pups born dead or die during abnormal parturition was 22.3
per cent (Darvelid and Linde- Forsberg 1994).
2
In view of considerable economy and owners concern involved, it becomes
extremely important to carry out comprehensive studies with regard to the factors
influencing the frequency of dystocia and various etiological factors. It is also important
to formulate guidelines on selection of treatment procedures in an attempt to reduce the
incidence of mortality of the dam and the neonate.
The course of parturition has been documented to be influenced by such factors as
the breed (Freak, 1962; Smith, 1974 and Gaudet, 1985), age (Freak, 1962 and Darvelid
and Linde-Forsberg, 1994), size (Christiansen, 1984) and parity (Gaudet, 1985 and
Darvelid and Linde-Forsberg, 1994) of the bitch. Studies on the factors influencing the
incidence of dystocia would help a Veterinarian to identify animals most commonly
predisposed for dystocia and decide on the course of action to prevent dystocia and
reduce the maternal and fetal mortality.
It is equally important to establish the cause of dystocia in each individual case
prior to initiation of therapy. Although, there is overwhelming evidence in canines that
maternal dystocias occur much more frequently than fetal dystocias (Gaudet, 1985 and
Darvelid and Linde-Forsberg, 1994), the treatment of dystocia, fetal or maternal, is
always to be considered as an emergency. Depending on the underlying causes of
dystocia, the obstetrician has three treatment procedures at his disposal: namely a).
Augment uterine contractions using ecbolics b). Attempt digital manipulation or forceps
delivery c) or perform a cesarean section. The choice of treatment is largely dictated by
the ability of the obstetrician to identify the cause of dystocia, the general health of the
mother, the viability of the fetuses and the familiarity with different obstetrical
3
procedures. In addition, the choice of treatment is also influenced by the duration of
dystocia which may significantly affect the puppy survival rate.
The present study therefore, was intended to document information on a series of
canine dystocias with the hope of assisting Veterinary clinician in decision making
process. The specific objectives of this study were
a. To analyze the influence of breed, age, size and parity of the dam on the
frequency distribution of dystocias in canines.
b. To record the frequency of occurrence of various forms of dystocia in bitch.
c. To study the effect of duration and type of dystocia on the survivability of
neonates.
d. To evaluate the relative efficacy of various treatment procedures employed to
relieve dystocia in canines.
e. To compare the efficacy of different anesthetic protocol used for cesarean section
on the safety of mother and neonates and
f. To study the influence of various anesthetic protocols on clinical and biochemical
parameters in bitches undergoing cesarean section.
Review of Literature
II. REVIEW OF LITERATURE
2.1 Duration of pregnancy
2.1.1 As the interval between a single or first of the multiple matings to the day of
parturition
The ability to precisely predict the duration of pregnancy is of practical
importance for managing parturition or for planning caesarean section. (Luvoni and
Beccaglia, 2006). Gestation length in dog, expressed as the interval from an initial or a
single mating to parturition is reported to range from 58 to 71 days (Anderson, 1973;
Holst and Phemister, 1971; Anderson and Simpson, 1973; Holst and Phemister, 1974;
Concannon et al., 1975; Sokolowski, 1980). Normal pregnancies as short as 57 days and
as long as 68 days have been reported after single mating (Holst and Phemister, 1974). In
one colony, gestation length of 57 to 72 days was encountered after the first of multiple
mating and 52 to 70 days after single mating (Concannon and Rendano, 1983).
Concannon et al., (1983) studied the variation in canine gestation length of 290 beagle
bitches and reported that the apparent gestation length estimated as the interval from day
of first mating to the day of parturition ranged from 57 to 72 days and averaged 65.3 ±
0.2 days. The wide variation reported in the gestation length of the dog when calculated
as the interval from initial or a single mating to parturition has been attributed to the
variations in the time of mating in relation to the time of fertilization (Concannon et al.,
1983) and Wildt et al., (1970) opined that a gestation length beyond 70 days after the
single mating was probably pathological.
5
Breed differences in gestation length, although not well documented, has been
postulated. Okkens et al., (1993) and Okkens et al., (2001) studying 113 bitches from 6
breeds found a mean gestation length of 62.8± 1.2 days, for West Highland White Terrier
which is significantly longer than 60.4±1.7 in German Sheppard, 60.9±1.5 days in
Labrador Retriever and 61.4± 1.0 days in Doberman. They also found a negative
correlation between mean length of gestation and litter size and concluded that the breed
is the main factor influencing the length of gestation and might be ascribed to breed
related differences in litter size. In contrast, Linde – Forsberg et al., (1999) studying
fertility data from 327 frozen semen AI’s found no influence of either breed or litter size
on gestation length.
Thomassen et al., (2006) in a study involving, 526 bitches of 99 different breeds
from 1994 to 2003 recorded significantly (P≤0.01) longer duration of pregnancy in
bitches with a litter size of less than 3 pups (61.7 ± 0. 4 days) than in bitches with larger
litters (60.5 ± 0.1 days).
Bruce et al., (2005) made a retrospective analysis to determine the effect of age,
breed, parity, and litter size on the duration of gestation in the bitch and found that the
age or parity has no significant effect on length of pregnancy period. However, they
reported that Labrador Retriever, German Shepherd, Golden Retrievers and hounds are
more likely to have a longer pregnancy period and also stated that longer pregnancy
duration is seen in bitches whelping four or fewer pups than those whelping five or more
pups; the prolongation averaging one day.
6
Polster (2006), have reported that single pups are carried for longer period (64.0
days) than litters with 2 to 6 pups (62.3% days) and more than 6 pups (62.7 days) and
they established the average of gestation period as 63.1 days.
2.1.2 On the basis of Ultrasonographic measurements of the gestational sac or fetal
head diameter
Real time ultrasonography has proven to be a valuable tool for diagnosing canine
pregnancy and assessing fetal viability (Inaba et al., 1984). Cartee and Rowlers (1984)
reported that, ultrasonographically the embryo in bitch was identifiable at day 10
following LH surge. Fetal and cardiac activities could be monitored at day 28 of
gestation. Similarly, Shille and Gontarek (1985) reported that viability of the fetus can be
judged by the presence of fetal movements after day 28 of gestation. Concannon (1986)
stated that real time ultrasound scanning allows direct visualization of vesicles and or
fetal movements and provided the ability to perform pregnancy diagnosis through the
post implantation period. The ultrasonographic appearance of a gravid uterus in Beagle
bitches at known time of gestation was studied in detail by Yeager and Concannon (1990)
and Yeager et al., (1992). They detected cardiac activity and fetal movements as early as
25 and 34 days respectively after LH surge. Mattoon and Nyland (1995) reported
detection of gestational sac at 20 days post breeding as the first sign of confirming
pregnancy using ultrasonography but preferred to wait until day 30 as gestational sac
with viable embryo could be identified with high level of confidence at that time.
Shille and Gontarek (1985) in a study involving 23 Grey hound bitches have
reported diameter of the gestational vesicle determined by ultrasound technique at
7
different stages of gestation. Pregnancy was timed from the calculated date of ovulation
to the day when first pup was born. The results revealed that the gestational sac diameter
increased as gestation days progressed. On days 27 to 34, 35 to 44 and 47 to 56 after
ovulation the average vesicle diameter ranged between 23 and 30mm, 25 and 49mm and
46 and 89 mm respectively with a mean diameter of 26.5mm, 36.1mm and 68.3mm
respectively.
England et al., (1990) attempted to determine the gestational age in 50 clinically
normal bitches. Ultrasonographic measurements were made on three occasions (early,
mid and late pregnancy) and were related to the date of parturition. The study revealed
that the diameter of spherical conceptuses during early pregnancy was significantly
related to gestational age. The study also showed that in bitches of similar size the
measurement of conceptus diameter, biparietal diameter and trunk diameter were closely
related to gestational age.
Yeager et al., (1992) used ultrasonography to estimate the gestational age in 8
pregnant Beagle bitches. The gestational age was based from day of preovulatory LH
surge which was denoted as “0”day of gestation. Serial ultrasonographic examinations of
each pregnant bitch began on day 28 to 37 after the LH surge. It was reported that
measurements of chorionic cavity diameter (CD) was the most accurate predictor of
gestational age. It had the least variation compared with all other measurements on the
fetus. From days 38 to 60, the fetal head diameter was the more accurate predictor of
gestational age.
8
Valocky et al., (1997) opined that best predictors of gestation age in early to mid-
pregnancy were CD and uterine lumen diameter. They also opined that gestational age is
best predicted from day 35 to term with measurements of biparietal diameter and head
diameter.
A study was under taken by Luvoni and Grioni (2000) to estimate the gestational
age in medium size dogs by ultrasonographic examinations. Formulae were derived to
estimate the expected date of delivery by measuring the anatomical fetal structures and
the gestational sac was found to be 90.9 per cent accurate and that of biparietal diameter
70.8 per cent accurate for predicting the date of parturition with ±1 day in medium size
dogs. The accuracy of prediction of date of parturition for small size dogs was 90.9 per
cent using gestational sac diameter and 68.2 per cent using biparietal diameter.
Son et al., (2001) stated that the ultrasonographic measurements of inner CD on
days 18 to 37 and fetal head diameter on day 38 to parturition showed the best correlation
to gestational age and prediction of parturition date.
Kutzler et al., (2003) carried out a retrospective study on fetal measurements
obtained by transabdominal ultrasonography of 83 bitches (32 breeds) to estimate the
gestational age using two published tables correlating embryonic vesicle diameter,
crown-rump length, body diameter and biparietal diameter to the LH surge in mid
gestation. Parturition was predicted by obtaining the difference between the gestational
age estimate and 65 days. Bitches were divided into four body weight groups based on
their non pregnant body weight small (<9 kg), medium (>9 to 20 kg), large (>20 to 40
kg), and giant (>40 kg). Litter size was obtained for each group. The body weight groups
9
were then divided into small, average and large litter size groups. The accuracy of the
prediction was not affected by litter size, but was affected by maternal body weight for
small and giant body weight groups only. When adjusted for weight, the accuracy of
prediction within ±1 day and ±2 day intervals was 75 and 87per cent, respectively.
Parturition date predictions made after 39 days of gestation using only biparietal and
body diameter were less than 50 per cent accurate with ± 2days.
Beccaglia and Luvoni (2006) studied the accuracy of ultrasonographic
measurements and suggested that inner CD and biparietal diameter were equally reliable
parameters in obtaining a reasonably accurate prediction of parturition date at any stage
of gestation period the bitch was examined.
Lenard et al., (2007) assessed the accuracy of estimating the gestational age and
litter size in 76 bitches using one or two techniques. The first method used the differential
features of fetal organ development that occur in early and mid pregnancy, based on
published tables for Beagles. The second method used biparietal head and trunk
diameters to predict gestational age based on tables published for late gestational period
for Labrador Retrievers. The accuracy of the two methods was compared to evaluate the
effect of maternal body weight and litter size. Litter size and maternal body weight did
not affect the accuracy of gestational age prediction. Using a combination of both the
methods, the overall accuracy of predicting parturition date to within 65 ± 1 day and ± 2
days was 70.8 per cent and 86.1 per cent, respectively. The correct litter size was
predicted in 65 per cent of cases and in 89.5 per cent of cases for ± 1 pup. It was
10
concluded that the optimum time for sonographic estimation of fetal age and litter size
was early and mid-pregnancy.
2.2 Physiological Changes in the dam during Pregnancy
2.2.1 Hematological changes
The dam and fetuses have an increased metabolic demand to meet this demand;
maternal blood volume progressively increases by approximately 40 per cent during
pregnancy. The increase in plasma volume is proportionally greater than the increase in
erythrocytes leading to hemodilution and relative anemia. (Pascoe and Moon, 2001;
Seymour, 1999). This progressive normochromic, normocytic anemia develops between
days 25 and 30 of pregnancy and is most severe at full term (Concannon, 2002).
Hematocrit values at full term can be as low as 30 per cent to 35 per cent. The degree of
anemia appears to be greater with an increasing number of fetuses (Kaneko et al., 1993).
A right shift in the maternal hemoglobin dissociation curve occurs, allowing more
effective delivery of oxygen to maternal and fetal tissue (Seymour, 1999). There is no
absolute decrease in erythrocyte mass and the hematocrit returns to normal within 8 to 12
weeks after parturition as the plasma volume returns to normal (Concannon 2002).
2.2.2 Cardiopulmonary changes
Increased cardiac output proportional to increased blood volume occurs during
pregnancy as a result of increased heart rate and stroke volume (Kaneko et al.,1993).
Peripheral vascular resistance decreases during pregnancy resulting from the increased
capacity of blood vessels in the uterus, mammary glands, kidneys, striated muscle and
cutaneous tissue, so that the mean arterial blood pressure is maintained and circulatory
11
overload does not accompany the increased cardiac output (Hall et al., 2001).
Compensatory cardiovascular baroreceptor mechanisms in response to hemorrhage or
hypotension may be attenuated during pregnancy (Brooks and Keil, 1994). Cardiac work
is increased and cardiac reserve is decreased during pregnancy (Seymour, 1999).
Animals with cardiac disease that were previously stable or well controlled on
medications can become decompensated and develop heart failure during pregnancy and
parturition (Thurmon et al., 1996; Seymour, 1999).
During pregnancy, there is decreased Functional Residual Capacity (FRC; the
remaining lung volume measured at the end of a normal expiration), decreased total lung
volume and increased minute ventilation and oxygen consumption (Pascoe and Moon,
2001). Decreased FRC and total lung volume are due to cranial displacement of the
diaphragm by the expanding gravid uterus (Greene, 1995).
Oxygen consumption increases because of the metabolic demands of the fetus,
uterus, and mammary glands (Hall et al., 2001). The combined effect of decreased FRC
and increased oxygen consumption makes dogs in late gestation very susceptible to
hypoxemia (Seymour, 1999). Any period of apnea can cause rapid maternal arterial
hemoglobin desaturation, decreased oxygen delivery to the fetus and hence, fetal
hypoxia. The most critical time for apnea is at anesthetic induction and so preoxygenation
with 3 to 5 L/min of 100 per cent oxygen by facemask before and during induction of
anesthesia is highly advisable to decrease the risk of hypoxemia (Seymour, 1999).
12
The arterial partial pressure of carbon dioxide (PaCO2) decreases during
pregnancy as a result of increased sensitivity of the respiratory center to carbon dioxide
and consequent increased minute ventilation. The normal PaCO2 in pregnant animals can
be as low as 30 to 33 mm Hg compared with 40 mm Hg in nonpregnant animals (Greene,
1995).
Hyperventilation either spontaneous (as can occur with stress, anxiety, or pain
during labor) or related to assisted ventilation under general anesthesia can worsen
maternal hypocapnia. Under conditions of hypocapnia, the maternal oxyhemoglobin
dissociation curve shifts to the left, increasing the maternal hemoglobin affinity for
oxygen (Bohr Effect) and decreasing oxygen transfer to the fetus (Greene, 1995)
Decreased FRC and increased minute ventilation in pregnant animals allow rapid
equilibration between inspired and alveolar inhalant anesthetic concentrations, making
induction of inhalation anesthesia more rapid than in nonpregnant animals (Seymour,
1999). The exact mechanism for this increase in sensitivity is unknown but is thought to
be related to increased serum progesterone concentrations exerting a depressant effect on
the central nervous system (Moon and Pascoe, 2001). Therefore, pregnant animals may
be at a higher risk of relative anesthetic overdose.
2.2.3 Renal changes
Renal blood flow and glomerular filtration rate increase during pregnancy as a
consequence of increased blood volume and cardiac output. This decreases the serum
urea nitrogen and creatinine levels compared with those in nonpregnant dogs (Gleed and
Seymour, 1999). Insulin resistance can occur during pregnancy as a result of a
13
progesterone-induced increase in growth hormone secretion by the mammary glands.
This may result in resistance to exogenous insulin therapy in pregnant diabetic bitches as
well as hyperglycemia in normal pregnant bitches (Concannon, 2002).
2.2.4 Gastro-intestinal changes
Dogs undergoing intra-abdominal procedures are at increased risk of silent
regurgitation during anesthesia (Galatos and Raptopoulos, 1995). Pregnant animals have
increased gastric acidity and the gravid uterus causes increased intra abdominal pressure
leading to reduced gastric and lower esophageal sphincter tone, making regurgitation
during anesthesia and possible aspiration or esophagitis more likely reported that
increases in acute phase proteins are assumed to represent inflammation-like responses to
the insult caused by implantation and placentation. Transient anorexia for several days
around day 28 is normal. Increased food must be supplied to account a 40 per cent
average increase in food consumption, which adds a 20 to 55 per cent increase in body
weight. Calcium or Vit D (or any additive) supplementation is contraindicated as they can
complicate normal calcium regulation increasing incidence of the peripartum
hypocalcaemia (Pascoe and Moon, 2001, Concannon, 2002).
2.3 Fetal Physiology
Drugs that are able to cross the blood–brain barrier are able to cross the placental
barrier (Pascoe and Moon, 2001). All anesthetics and sedatives cross the blood–brain
barrier to exert their desired effects on the CNS; thus they inevitably cross the placenta
and exert an effect on the fetus.
14
Dogs have an endotheliochorial placentation and large areas of zonular
implantation, allowing easy transfer of drugs from the maternal circulation to the fetus by
simple diffusion (Cunningham, 2002). Most anesthetics have a low degree of protein
binding, low molecular weight, high lipid solubility and poor ionization properties that
are associated with a ready ability to cross the placental barrier and exert an effect on the
fetus.
2.3.1 Fetal circulation
Fetal circulation differs from adult circulation in that oxygenated blood enters the
fetus at the level of the splanchnic circulation. Maternal blood that is delivered to the
fetus via the umbilical vein has a low partial pressure of oxygen (PO2) typically 40 mm
Hg (Seymour, 1999). To make efficient use of this blood, fetal hemoglobin has a greater
affinity for oxygen than does maternal hemoglobin resulting in greater fetal hemoglobin
oxygen saturation (Cunningham, 2002). This difference between fetal and maternal
hemoglobin is greater in ruminant species than in dogs. Eighty per cent to 85 per cent of
this blood enters the liver, where most of it bypasses the liver parenchyma via the ductus
venosus to enter the caudal vena cava, where it mixes with venous blood (Greene, 1995;
Thurmon et al., 1996). The PO2 of fetal blood returning to the right atrium is
approximately 25 mm Hg, so the fetus is in a constant state of relative hypoxemia
compared with maternal values.
Any cause of maternal hypoxemia can lead to fetal hypoxia and acidosis. Fetal
hypoxemia stimulates vasodilation in the fetal heart and brain and vasoconstriction in the
pulmonary vasculature, gut, kidneys, and skeletal tissue (Cunningham, 2002).
15
Anesthetics entering the fetal circulation are partially metabolized by the fetal liver and
diluted with blood from the caudal circulation before passing to the fetal heart and brain
(Seymour, 1999). The clinical effect of fetal circulation is that the heart and brain are
relatively protected from perfusion with blood containing high concentrations of
anesthetics. Anesthetics that have a short half-life have short peak concentrations in the
mother and fetus whereas, anesthetics that are administered continuously (e.g., volatile
inhalation agents, constant-rate infusion injectables) may have a persistent depressant
effect. Volatile inhalation anesthetics have marked cardiovascular and respiratory
depressant properties. Selection of inhalation anesthetics with a low blood solubility and
maintenance of the lowest possible gaseous anesthetic concentrations are recommended
to minimize neonatal depression.
2.3.2 Fetal Hepatic system
The hepatic microsomal enzyme systems responsible for drug metabolism are
incompletely developed or absent in neonatal puppies and take 3 to 5 weeks to reach
adult levels (Grandy and Dunlop, 1991). Drugs that undergo hepatic metabolism have a
longer duration of effect in fetuses or neonates (Greene, 1995).
2.4 Signs of Impending Parturition
Freak (1975) described the signs of impending parturition in bitch as restlessness,
apprehension, refusal of food, possible vomiting to get rid of the solid or fluid content
from stomach, shivering, glaring at flank and intensified effort at scraping out rest. The
attitude to the owner’s presence was reported to vary among individuals. Some insisted
on a reassuring presence of owner or even another bitch, others sought solitude and a
16
dark onset under cover. The author stresses that, it is important to recognize this variation
in behaviour because, misinterpretation or mismanagement of this aspect could lead to
voluntary inhibition of labour.
Buckner (1979) noted that, bitches signal impending labour by uneasiness,
anorexia, emesis, glancing at flank and shivering. He stated that the appearance of milk in
the teat canals is extremely variable and it may appear several days to hours prior to
visible labour or concurrently with whelpings. The period of impending labour lasted 6 to
12 hours or as long as 36 hours after appearance of milk in the teats.
Concannon (1986) observed that 2 to 3 days prior to parturition the bitches
usually became restless, sought seclusion and reduced the food intake. During 12 to 24
hours prior to parturition, there was an increased restlessness, panting, scratching,
chewing and nesting behaviour.
Mosier (1986) stated that, signs of approaching parturition in bitch were
characterized by dam’s anxiety, restlessness and intermittent nest making. A decrease in
her activity and appetite may occur as early as seven days before whelping and milk may
be present in the mammary glands 2 - 3 days before stage one of parturition in primipara
but, in multiparous bitches it is not uncommon for milk to be present as early as seven
days before the birth of first puppy.
Arthur et al., (1989) stated that the imminent signs of approaching of parturition
in bitch are indicated by the animal preparing her bed, restlessness, indifference to food
and an inclination to pant and these changes were most obvious in primigravid. Wallace
17
and Davidson (1995) described as signs of impending parturition in bitch such as
restlessness, panting, chewing and scratching of bedding material.
Normal parturition is divided into three stages with predictable signs of
forthcoming labor and restless behavior, anorexia and nesting may all be seen several
days before parturition as well as during stage 1 of labor. Mammary gland turgidity, milk
secretion and relaxation of pelvic and abdominal musculature are also described.
(Feldman and Nelson 1996; Linde-Forsberg and Eneroth 2000; Wykes and Olson, 2003).
A decline in rectal temperature below 99.7°F (37.6°C) has been cited as the most
consistent change indicating that parturition will take place within the next 12 to 24
hours. (Linde-Forsberg and Eneroth 2000; Wykes and Olson 2003; Schweizer and
Meyers-Wallen, 2000). Lochial discharge, produced by hemoglobin breakdown, is
normal after parturition and is associated with uterine involution. The discharge is green
to reddish brown, odorless and persists for up to 6 weeks. (Wykes and Olson 2003,
Macintire 1994).
Long et al., (1978) noted that the most consistent and reliable physical sign of
impending parturition in pregnant laboratory beagle bitches is palpable relaxation of
pelvic and abdominal musculature and opined that drop in rectal temperature is of some
value but found to be too variable between individuals to use as the sole criterion.
Veronesi et al., (2002) noted statistically significant increase in body temperature
beginning 12 hours after the onset of parturition and also opined that, if any significant
increase in body temperature is recorded at the end of pregnancy without the beginning of
the expulsion of fetuses, it could indicate problems of parturition.
18
2.5 Stages of Parturition
The various stages of parturition in bitch have been well described by Mosier
(1986) and Andrew et al., (2007).
2.5.1 First Stage of Parturition
The first stage of parturition begins with indiscernible uterine contractions and
progressive cervical dilation. This stage lasts 6 to 12, hours but in primiparous bitches it
may persist for up to 24 hours. Behavioral signs associated with stage-1 labor include
nesting, panting, and restlessness (Andrew et al., 2007).
Mosier (1986) states that the first stage of parturition lasts from 1 to 36 hours with
a mean duration of 6-12 hours. The signs similar to those observed in a bitch approaching
parturition were also described during the first stage of parturition. Active contractions of
both longitudinal and circular muscle fibres of the uterus were most intense and seen first
anterior to the most caudal foetus. Dilatation of cervix begin at the external os, the pelvic
ligaments relaxed and mucus passed through the cervix during the 12 hours preceding the
end of the first stage and the uterine contractions then occurred at progressively closer
intervals. Near to the end of the first stage the most caudal foetus rotated on its long axis
and extends the head, neck and limbs. Four hours before the end of the first stage the
dam’s cervix dilated to approximately 8 mm diameter (Smith and Donald, 1974). The
allantochorionic membrane appeared in the vagina near the end of stage one and its
rupture resulted in discharge of fluids. Shortly after the rupture of allantochorionic
membrane, the amniotic sac passed through the vagina and protruded as water bag
between the lips of the vulva signaling the onset of stage two (Mosier, 1986).
19
2.5.2 Second Stage of Parturition
The second stage of parturition is the stage of propulsion and expulsion of pup or
of straining and delivery (Freak, 1975). Andrew et al., (2007) have stated that the second
stage of parturition is the active expulsion of the fetus from the birth canal; the visible
abdominal straining matches the strong uterine contractions. Clear vaginal discharge, the
allantoic fluid, is seen as stage-2 labor begins and precedes each puppy. Abdominal
contractions and or presence of foetal membranes at the vulva are the signs of onset of
second stage of labour. A dam will usually be on her side during this stage although, it is
not uncommon for her to stand intermittently, strain and occasionally deliver a foetus
while standing (Mosier, 1986; Johnston 1986).
The intermittent uterine contractions of the first stage start to propel the foetus
towards the cervix. As the foetus is forced in to the cervix and mechanically dilates it,
neurohormonal reflex (Furgusons reflex) results in further increase in circulating
oxytocin and intensifies uterine contractions. (Furguson, 1941). As the foetus approaches
the pelvis, the outer layer of the foetal membranes the allantochorion reaches the vulva
and ruptures or is torn by the bitch (Freak, 1975 and Roberts, 1986). The rather tougher
layer of the amnion paases into the pelvis. At this moment, the foetus is engaging the
pelvic inlet in already rotated position and extended posture (Freak, 1975). Freak (1962)
also stated that the foetus which dies before reaching the pelvic inlet almost invariably
remains unrotated. As the foetal head in a normal anterior presentation engages fully in
the pelvis, its pressure stimulates a neural reflex which brings forceful abdominal
straining into play to assist propulsion of head and shoulders through the pelvis. In
primigravid, the lips of the vulva may offer slight resistance and may require greatest
20
expulsive effort (Roberts, 1986; Freak, 1975 and Mosier, 1986). Usually, once the head is
through the vulva, the foetus slides out easily, the bitch rips opens the amnion with her
incisors, cleans the nose of the pup and by licking pushes the membrane posteriorly over
its abdomen until the pup lies free, breathing normally but still attached by the umbilical
cord. At this point the umbilical cord is usually severed by the bitch by biting.
The first pup is usually born within four hours after the onset of second stage of
labour (Johnston, 1986 and Wallace and Davidson, 1995). On the other hand, Mosier
(1986) reported that the first foetus is usually delivered within 20 to 30 minutes after the
onset of second stage of labour.
Roberts (1986) also stated that, straining may begin half to one hour or more
before the second pup is expelled. The average total time for the second stage of the
parturition is 3 to 6 hours and 12 hours is considered to be maximum. Freak (1962)
noticed that the time period between the deliveries in bitch is extremely variable. In the
normal easy whelping breeds, 10-30 minutes is considered as the usual period. In a very
large litter, a group may be born at this rate followed by a rest of even upto 4 hours,
before a final one, two or three puppies followed.
Buckner (1979) recommends the examination of the bitch, if she has whelped one
or more puppies and then fail to deliver other fetus(s) present in the uterus during next
hour and that a bitch should not be allowed to labour vigorously at the onset of parturition
for more than two hours without delivering a puppy.
Bennet (1980) considers the following criteria for diagnosing dystocia in the bitch
(a) Strong and persistent expulsive effort failing to deliver a puppy within 20 to 30
21
minutes. (b) Weak infrequent expulsive effort failing to deliver a pup within two hours
and (c) more than 4 hours having elapsed since the birth of a puppy with no evidence of
further labour.
Roberts (1986) stated that, it may take about one hour of labour for the first pup to
be born. Following the delivery of first pup the dam may rest for a variable period of time
and the rate of expulsion of subsequent pups being vary irregularly but progressively
shorter.
Johnston (1986) also stated that subsequent puppies are generally delivered at
interval of less than two hours each and that many bitches will deliver two puppies within
minutes of each other and then rests while, some bitches will deliver entire litter in two to
four hours and others may take 6-12 hours. The author concludes that, failure to progress
is generally defined temporarily as occurring when the bitch had been in the second stage
of labour for more than two hours prior to the birth of her first pup or more than two
hours between pups.
Arthur et al., (1989) reported that the total time occupied by the second stage will
depend chiefly on the number of the fetuses, but as a general rule when the litter is within
the usual limit of 4 to 8 puppies it occupies about 6-12 hours and it is improbable that the
puppies born after this time even without assistance will be alive.
22
2.5.3 Third stage of parturition
The third stage of parturition is the expulsion of the fetal membranes, which takes
place 5 to 15 minutes after the delivery of the fetus. Multiple placentas may be passed
after several puppies are delivered close together (Andrew et al., 2007).
2.6 Factors influencing dystocia in dog
2.6.1 Breed
Breed of the dam has been reported by several authors to have significant
influence in the course of parturition in the bitch (Freak 1948, Freak 1962, Health 1963,
DeMaar 1968, Bennet 1974, Donovan 1980, Shille 1983, Jones and Joshua 1988, Polster
2006, Catharina and Gunilla, 2007 and Chatdarong et al., 2007). The Boxer suffers a high
frequency of dystocia, mainly due to uterine inertia, but also due to fetal malpresentation
(Catharina and Gunilla., 2007).
The Welsh Corgi shows extreme variation in the size of the pup and hence
absolute fetal over size as also in a majority of miniature breeds (Wright, 1939 and Freak,
1948). Primary uterine inertia is also reported to be more common in many Terries and
Cocker Spaniels (Freak, 1948). Freak (1962) reported that, out of 222 cases of dystocia,
121 occurred in Scottish Terrier and 6 occurred in miniature and toy poodles. Of the other
breeds involved, Mongrels had the next highest incidence of 16 cases. Smith (1965)
stated that in bull dogs, a chord like structure crossing the lumen of the vagina dorso-
ventrally just caudal to the cervix was observed as a cause of dystocia.
23
Roberts (1986) stated that, the highest incidence of dystocia are encountered in
Boston Terrier, Scotch Terrier, Pekinese, Sealghm and other small brachiocephalic
breeds and lowest in the more natural breeds such as hounds and mongrels. He
considered the disproportion between foetal size and maternal pelvic diameter as the
primary reason for higher incidence of dystocia in toy and achondroplastic breeds.
Smith (1974) stated that, a relatively small pelvis is the contributing factor for
dystocia in Bosten Terriers. Christiansen (1984) claimed that, dystocias mainly occurred
in the miniature breeds because their pups are bigger in relation to the bitch compared
with the case in medium and large breeds.
A retrospective study by Gaudet, (1985) involving 128 cases of canine dystocia
revealed Chihuahua, Dachshunds, Perkingese, Yorkshire Terrier, Miniature Poodles and
Pomeranian to have significantly increased risk of dystocia. However, the study did not
support the reported high incidence of dystocia for brachycephalic breeds.
Arthur et al., (1975) noted that, Dachshunds and Aberdeen Terrier to be
particularly prone to primary uterine inertia. The Corgi showed extreme variation in the
size of its puppies and hence absolute and relative oversize leading to dystocia.
Brachiocephalic breeds together with the Scalyham and Scottish terrier were said to be
more prone to obstructive dystocia due to foetuses having comparatively large head and
the dam having narrow pelvis.
Moon et al., (1998) in their study to determine perioperative management and to
calculate survival proportions in dogs undergoing cesarean section in the United States
and Canada found that the most common breeds of dogs that underwent emergency
24
surgery are Bulldog, Labrador Retriever, Boxer, Corgis, and Chihuahua and the most
common breeds of dogs that underwent elective surgery were Bulldog, Labrador
Retriever, Mastiff, Golden Retriever, and Yorkshire Terrier.
Although dystocias are rare in Grey hounds (Sweeney, 1972), this breed showed a
high proportion of dystocia case due to arrested foetal development and foetal death
(Freak, 1948). Bennet (1974) started that, bull dogs sometimes have slack abdominal
musculature making it impossible for abdominal straining to lift the fetuses upto pelvic
cavity.
2.6.2 Age
Freak (1962) reported that, in 16 cases of dystocia in mongrels 12 of them were
over five years of age and 11 of which showed inertia and oversized foetus associated
with low fecundity. Freak (1975) reported that, the dams aged 5 years and above were
more prone for complete primary uterine inertia. Smith (1965) also stated that, older
bitches particularly those which are oversized and improperly exercised are particularly
prone to development of uterine inertia.
Polster (2006) reported that 4.4 years is the average age of the obstetrically treated
bitches and also stated that the average age of patients in relation to the causes of dystocia
are higher in the following: weak contractions (maternal) 4.5 years and single whelps
(foetal) 5.2 years.
Gaudet (1985) found that, no single age of the dystocia patients varied
significantly when compared with overall intact female hospital population. In a total of
128 cases of dystocia, 24 were less than 2 years, 60 between 2 and 4 years, 25 between 5
25
and 7 years, 10 between 8 and 10 years and 3 over 10 years, with the age being unknown
in 6 other dams.
Darvelid and Forsberg (1994) could not clearly establish the influence of age on
the incidence of dystocia in bitch. In their study 39 per cent of the bitches were between 2
and 8 years of age.
2.6.3 Parity
In retrospective study of 128 cases of canine dystocia Gaudet (1985) found that,
37 per cent of the animals presented were primigravid.
Darvelid and Forsberg (1994) reported that, 28 per cent of the bitches
experiencing dystocia had not littered before, 15 per cent had one litter, 15 per cent had
two litters and 2 per cent had more than 2 litters. Further, 42 per cent of bitches which
had whelped before also had problems during the previous parturition.
Polster (2006) in their study reported that 41.4 per cent of the patients needed
obstetrical treatments were bearing their first litter. They also noted that chances of
dystocia were lower as the number of pups per birth was higher.
2.6.4 Size
Polster (2006) stated that the possibility of dystocia is much higher in small
breeds and found that 41.0 per cent out of 698 cases treated the miniature breeds were
over represented in comparison to other breeds.
26
2.7 Incidence of dystocia
Gill (2002) opined that the overall incidence of dystocia in the bitch is probably
below 5 per cent but it may amount to almost 100 per cent in some breeds of dogs,
especially those of the achondroplastic type and those selected for large heads and also
stated that in a study of 15 breeds of dogs he found varying frequency of dystocia from
9.1 per cent in Golden Retrievers to 85.7 per cent in Pekingese and caesarian section was
required in 5.9 per cent Rough Collies and 60 per cent in Pekingese. Eneroth et al.,
(2000) reported frequency of caesarian sections in Boston Terriers as 62 per cent while it
was 43 per cent in French Bulldogs. Recently, Bergstrom et al., (2006) using data from
insurance claim records from almost 200,000 insured bitches in the period 1995–2002,
estimated the overall incidence of dystocia to be around 16 per cent and caesarian section
was performed in 63.8 per cent cases.
2.8 Causes of dystocia
The Veterinarian handling dystocia is largely concerned with correcting or
relieving the immediate interference to birth, which have been traditionally classified into
foetal or maternal in origin (Bennet, 1974; Smith, 1974; Arthur, 1975; Buckner, 1979;
Johnston, 1986; Arthur et al, 1989; Darvelid and Forsberg, 1994 and Wallace and
Davidson, 1995). Smith (1974) stated that, foetal dystocia are more common than
maternal and is caused by abnormalities in the size, confirmation or presentation of one
or more puppies at same time.
Gaudet (1985) in a retrospective study of 128 cases of dystocia in bitches reported
that, 57 (60%) of the cases were deemed to be due to primarily to a maternal anatomical
27
or physiological abnormalities. In a similar retrospective study involving 182 cases of
dystocia in bitches, Darveild and Forsberg (1994) found that 75 per cent dystocia were of
maternal origin caused by some anatomical or physiological abnormalities in bitch.
In a study of 182 bitches of different breeds that were brought to a Veterinary
hospital because of dystocia, Darvelid & Linde-Forsberg Darvelid, (1994) found that 75.3
per cent of the cases of dystocia had a maternal cause while 24.7 per cent are of fetal
origin. Gaudet, (1985), in a similar survey reported that 60 per cent of dystocias were due
to maternal causes while 40 per cent had foetal causes. Polster (2006) in their analysis
698 cases treated for obstetrical disorders found maternal dystocia (57.6%) outnumbers
the foetal dystocia (42.4%).
2.8.1 Maternal causes of dystocia
According to Arthur (1975) dystocias which arise in the mother are due to either
constriction of birth canal or to a deficiency of expulsive forces. The constrictive forms
most frequently encountered are inadequate pelvis, incomplete dilatation of cervix,
uterine torsion and congenital malformation of the birth canal.
2.8.2 Pelvic inadequacy
The area and the shape of the dam’s pelvic inlet and volume of the pelvic cavity
constitute an important group of factors necessary for unassisted delivery (Sloss and
Dufty, 1980). In an analysis of various causes of dystocia in bitch Freak (1962) observed
that abnormalities of maternal pelvis, in only one of 222 cases of dystocia treated over a
period of 15 years. However, the author also reported 77 cases of dystocias due to
relative oversize of the foetus, 64 of which were in Scottish Terriers. The author
28
concluded that, in this breed dystocia is partly caused by the pelvic diameter of the bitch,
which is common with that in other achondrsplastic breeds, is greater in the horizontal
plane than in vertical plane.
Smith (1974) agreed that, a small pelvis as a contributing factor for dystocia in
Boston Terriers. He also states that the most common abnormalities of the pelvis are a
healed fracture which reduces the size of the pelvic canal and alters the contour of the
pelvic griddle. The author also opined that obstructive malformations of the pelvis
resulting from bone disease are relatively rare in canines.
Freak (1975) also stated that, abnormal bony pelvis was fairly common in
Scottish Terrier and make the posteriorly presented foetus a hazard in this breed. Gaudet
(1985) reported in a retrospective study involving 128 cases of canine dystocia, five cases
were attributable to maternal anatomical abnormalities. In a similar retrospective study
Darveild and Forsberg (1994) reported that a narrow birth canal accounted for 1.1 per
cent of all maternal causes of dystocia.
Compton (1987) opined that clinically all pelvises can be categorized into
adequate, questionable, and too small. He stated that latter group is the least common and
generally includes the congenitally or developmentally abnormal pelvises and in most
cases cesarean section should be the mode of delivery. In all other pelvises with a vertex
presentation, a trial of labor is indicated because the fetal head is an excellent pelvimeter.
With proper fetal monitoring with an intrauterine pressure catheter, with the use of a
partograph to assist in the diagnosis of an active-phase arrest, followed by a cesarean
section at the appropriate time, there is no increase in fetal or maternal morbidity.
29
2.8.3 Abnormal maternal soft structures
Persistence of Mullerian duct in the shape of a pillar of tissue running from
vaginal roof to floor that may constitute an obstruction causing dystocia (Freak., 1962;
Herr., 1978 and Darvelid and Forsberg., 1994). The other rare forms of maternal tissue
abnormalities causing dystocia include vaginal prlolapse (Wilkinson, 1961; Wilson and
Rajendran, 1961; Schutte, 1967; Troger, 1970 and Memon et al., 1993) abscess and
neoplasm (Gaudet, 1985), a cord like structure crossing the lumen of the vagina
dorsoventrally just caudal to the cervix and other congenital anomalies (Smith, 1965).
2.8.4 Incomplete dilatation of cervix
Insufficient dilatation of cervix is reportedly not an important entity on its own,
but seen commonly as a part of primary uterine inertia (Bennet, 1974). The abnormalities
of uterus that cause dystocia in canines although less common include uterine rupture
(Rudolph et al., 1931; Allock and Panhale, 1952; Schlotthauer and Wakin, 1955 and
Ficus and Hallenberg, 1971) and uterine torsion (Kulkarni et al., 1965; Smith, 1965;
Tompsett, 1971; Brown, 1974; Prabhakar et al., 1995). Dover (1966) described an
abnormality of uterus, where the body and the first inch of both the horns were formed by
thin fibrous tubes causing failure to deliver the pups and Keen, (1966) recorded single
case of dystocia caused by aberrant round ligament encircling each uterine horn.
Gaudet (1985) reported dystocia in bitch due to severe uterine adhesions from previous
caesarean ection. The presence of gravid uterine horn in an inguinal region as a rare cause
of dystocia has been published in several case reports (Gotze, 1960; Health, 1963; Short,
1963; Ellet and Archibald, 1965 and Arthur et al., 1989).
30
2.8.5 Deficiency of expulsive force
2.8.5.1 Uterine inertia
Uterine inertia is probably the most common cause of canine dystocia with an
incidence estimated to range from 70 per cent to 90 per cent of all dystocia cases
Romagnoli, (2007). Acute respiratory alkalosis may be associated with the onset of
whelping, which would reduce the amount and delay the secretion of para thyroid
hormone in response to increased calcium demand. Subsequent subclinical
hypocalcaemia would lead to uterine inertia with delayed delivery and intrapartal hypoxia
of puppies (Gaudet, 1985).
2.8.5.2 Primary complete uterine inertia
Primary complete uterine inertia has been recognized as one of the principle cause
of dystocia in bitch. The condition is characterized by the failure of uterine muscle to
expel normal sized fetuses through birth canal which is normal, except perhaps for an
incompletely dilated cervix and characterized by contraction which are either completely
absent, weak or infrequent (Bennet, 1974).
Freak (1962) reported 25 cases of primary complete uterine inertia in a series of
222 cases of dystocia handled over a period of 15 years. The commonest single cause was
low fecundity. The author suggested that low fecundity and its accompanying low
hormonal influence appears to result in simple and complete failure to initiate whelping.
However, complete primary uterine inertia was also recorded in 3 cases with high
fecundity presumably due to uterine distension. Since most cases of primary complete
uterine inertia were recorded in Scottish Terrier, the author believed that, atleast in this
31
breed there is a hereditary predisposition. He has also reported, nervous voluntary
inhibition of labour in 17 of 222 cases of canine dystocia. Jackson (1972) reported 37 per
cent cases of primary complete uterine inertia out of 200 cases treated in Veterinary
practice in England.
The condition has been reportedly seen more frequently in bitches of 5 years and
above, often of low fecundity with three or fewer fetuses (Freak, 1975) and particularly
among the first litter bitches which were taken away from their familiar environment.
Among the factors suggested to be responsible for voluntary inhibition of labor include
unfamiliar surroundings and lack of reassurance of an owner’s presence (Freak, 1975).
Psychic disturbances are also said to be an important cause of uterine inertia in bitches.
Obesity and lack of exercise have also been suggested to be one of the causes of primary
complete uterine inertia (Buckner, 1979).
Gaudet (1985) reported that primary complete uterine inertia accounted for 7.9
per cent of all maternal causes of dystocia.
Johnston (1986) described the diagnosis of primary complete uterine inertia in
detail. The bitch with primary complete uterine inertia was generally bright and alert with
partial to complete cervical dilatation and exhibit a typical green tinged vaginal discharge
with weak uterine contractions. The author also stated that these patients were generally
normocalcemic and show no response to the administration of calcium and oxytocin and
that it may recur at subsequent pregnancy.
The cause of primary complete uterine inertia appears to be multiple and include
an inherent weakness in the uterine muscle such as in Scottish terrier breed.
32
Overstretching of myometrium by an excessively large foetus, hydroallontois or
unusually large number of fetuses, toxic degeneration due to bacterial infection, fatty,
infiltration of myometrium and senility (Arthur et al., 1989).
Darvelid and Linde-Forsberg (1994) reported that, primary complete uterine
inertia accounted for 68 per cent of all maternal causes of dystocia in bitch. Further,
nearly 90 per cent of the bitches with primary complete uterine inertia had only one or
two pups. Similarly, in other studies several other authors have also demonstrated that the
small litter size is an important cause of primary complete uterine inertia in bitch (Freak,
1962; Jones and Joshua, 1988 and Arthur et al., 1989).
Catharina and Gunilla (2007) reported that the most common reasons for dystocia
are primary uterine inertia (60%) and malpresentation of the fetus (26%).
2.8.5.3 Primary partial uterine inertia
Gaudet (1985) defined partial primary uterine inertia as those in which the second
stage of labour begins, few pups are delivered but uterine contractions diminish or
become ineffective prior to the delivery of the entire litter. In his studies involving 95
cases of dystocias partial primary uterine inertia were encountered in 33 dams.
Darvelid and Linde-Forsberg (1994) encountered partial primary uterine inertia in
42 of 182 cases of dystocia in bitch.
2.8.6 Foetal causes of dystocia
The foetal causes of dystocia include absolute oversize, mal presentation, position
and posture and monstrosities.
33
2.8.6.1 Absolute foetal oversize
Dystocia due to absolute foetal oversize is generally found in dams carrying
single foetus or in breeds showing great disparity in foetal size. In a series of 272 cases of
canine dystocia absolute oversize as a cause was encountered in 13 cases (Freak, 1962).
Smith (1965) stated that, large foetuses are most frequent in pregnancies in which only
one or two foetuses are present and the abnormally huge head in brachycephalic breeds
contribute to the high incidence of dystocia. Gaudet (1985) in his retrospective study
reported an incidence of 13.7 per cent dystocia due to oversized foetus. However,
oversized foetuses were found to be responsible for 6.6 per cent of cases of dystocia in a
study conducted by Darvelid and Forsberg (1994).
2.8.6.2 Malpresentation, position and posture
Freak (1948) reported that anterioventral position and breast head disposition
were the two most common causes of foetal dystocias in canines. Freak (1962) reported
that, mal-presentations other than posterior presentation were responsible for dystocias in
12 of 222 cases studied. Gaudet (1985) encountered 13.8 per cent dystocias in bitch
caused by foetal mal-orientation in the birth canal which include transverse presentation,
posterior flexed limbs and anterioventral position.
Darvelid and Linde-Forsberg (1994) encountered foetal dystocias in 24.7 per cent
of the cases. In their study involving 182 cases of dystocia in bitch, mal-orientation of
fetuses was encountered in 28 bitches, 9 of which were due to transverse presentation, 7
due to breech presentation, 4 due to neck flexion, 3 due to ventral presentation, 2 cases
34
each due to head flexion and double bent fetuses and a solitary case of simultaneously
presented fetuses.
Death of fetuses near the end of first stage of parturition has also been reported as
one of the common cause of dystocia, as such dead fetuses have high proportion of faulty
disposition due to failure of rotation of fetuses and extension of head and limbs (Freak,
1962; Bennet, 1980; Mosier, 1986 and Darvelid and Linde-Forsberg, 1994).
2.8.6.3 Foetal malformations
Foetal malformations such as foetal anasarca, hydrocephalus and incomplete
development of skull and brain have been reported as a cause of dystocia in canines
(Curwnan, 1948).
Gaudet (1985) reported that, 42 per cent litter contained puppies with congenital
deformities that resulted in dystocia. Malformations of pups were recorded in 17.6 per
cent of the litters in a study by Darvelid and Linde-Forsberg, (1994) but, were considered
to have caused dystocia in only three cases. The deformities noted included spina bifida,
abnormal hernias and malformations of the rib cage.
2.9 Blood biochemical studies
Emily et al., (2006) reported that serum biochemical concentrations remained
within normal limits even when adjusted to account for hemodilution and also stated that,
hematological and serum biochemical profiles in pregnant bitches do not differ
significantly from those found in normal adult dogs.
35
2.10 Electrocardiography
An overall increase in systolic pressure occurs during labor, as a consequence of
stress and pain, regardless of the obstetric condition (Lucio et al., 2008). The
cardiovascular depressant effects of some anesthetics (Propofol) are well tolerated in
healthy animals, but these effects may be more problematic in high-risk patients with
intrinsic cardiac disease as well as in those with systemic disease. In hypovolemic
patients and those with limited cardiac reserve, even small induction doses of Propofol
(0.75-1.5 mg/kg i/v.) can produce profound hypotension. (Short and Bufalari 1999). The
increased heart rate during pregnancy and lactation reflect increased demands on the
cardiovascular system and may be important to consider in clinical practice (Olsson et
al., 2003).
2.11 Evaluation of treatment procedures
2.11.1 Medical treatment
2.11.1.1 Oxytocin
Mc Donald (1965) opined that posterior pituitary extracts remains a useful agent
to reinforce weak uterine contractions provided the cervix is open and the uterine muscles
are not under tension. Prior to administering oxytocin it is recommended that, the
clinician should ascertain the position and presentation of most caudal fetus, that there are
no pelvic, vaginal and vulvar abnormalities and that the cervix is dilated (Mosier, 1986).
Variuos workers have frequently employed oxytocin either as posterior pituitary
extract or in a synthetic form to augment uterine contractions. In such cases oxytocin has
36
been commonly injected in doses of 5-20 IU subcutaneously or intramuscularly (Freak,
1962 and Mosier, 1986), 3-20 IU intramuscular (Johnston, 1986), 5-15IU intramuscular
(Arthur et al., 1989) or 0.5-1 IU per lb body weight intramuscularly (Wallace and
Davidson, 1995)
Freak (1962) stated that, while oxytocin is effective in early stages to overcome
partial inertia, the uterus tends to lose its sensitivity towards the end of the prolonged
parturition and its effect is relatively lower to deliver the final pup in large litter (Arthur,
1975).
Jonhston (1986) recommended an interval of 30 minutes between oxytocin
injections and if there is no progress even after three injections caesarean section is
recommended. He also noted that, the possible adverse effect of oxytocin therapy such as
premature placental separation may occur. The author also stated that the most domestic
females become refractory to oxytocin after repeated injections. Mosier (1986) reported
that, the effect of single dose will last approximately 15 minutes and recommend that
when repeated doses were given there should be minimum interval of 30 minutes
between the injections.
A recent study indicated that low plasma oxytocin concentrations are a cause of
primary uterine inertia in bitches with normal serum calcium concentrations and the
condition aggravate in bitches with low calcium levels (Bergstrom et al., 2006). This
explains the interrelationship between oxytocin and calcium in the medical management
of dystocia. The study also showed that only about one-third of the bitches responded to
37
oxytocin alone indicating that calcium may be very beneficial in many cases of dystocia
in which medical management is appropriate.
When oxytocin has been used alone, doses have historically been reported as high
as 5-20 IU administered IM in the dog. However, recent data suggest that doses as low as
0.5-2 IU are more effective in increasing the frequency and quality of the contraction
(Davidson, 2001). Initial doses of 0.1 IU/kg are recommended and the dose can be
increased incrementally to a maximum of 2 IU/kg (never exceed 20 U/dog in any breed)
are recommended. Johnston et al., (2001) advocate oxytocin administration at 30-40 min
intervals.
2.11.1.2 Calcium
For proper function and response, neuromuscular tissues are dependent upon a
normal balance of electrolytes within the body. In particular, uterine contractions are
dependent upon adequate levels of calcium (Pamela, 2001). In cases where calcium
metabolism has been compromised (i.e. by inadequate diet, by dietary supplementation of
a nutritionally balanced diet exogenous calcium during pregnancy, or by extended
periods of uterine contractions as seen in long deliveries), mildly depleted levels of serum
calcium within a whelping bitch may inhibit the normal progression of delivery by
interfering with uterine contractions (Pamela, 2001). Although hypocalcemia is usually a
problem in mid lactation, the condition can arise as a parturient complication. Freak
(1975) observed that, some subclinical hypocalcemic bitches may not show the typical
tremors and incoordination but, may exhibit restlessness coupled with uterine inertia.
38
Gaudet and Kitchell (1985) opined that, although dystocia due to hypocalcaemia
is rarely confirmed by laboratory analysis it should be assumed to be present in cases of
uterine inertia that fail to respond to oxytocin administration. Their study documented
atleast 16 cases in which propulsive uterine contractions recorded following calcium
therapy which had not responded to oxytocin administration.
Darveild (1989) reported that calcium and or oxytocin treatment was successful in
relieving dystocia due to uterine inertia in 44 of 181 cases (24.3%). In hypocalcemic
bitch, slow intravenous injection of calcium borogluconate is usually recommended
(Buckner, 1979; Bennet, 1980 and Johnston, 1986).
Several other studies have also documented the beneficial effect of calcium
administration in bitch with dystocia due to uterine inertia (Smith, 1965; Bennet, 1974,
Donovan, 1980; Shille, 1983; Gaudet, 1985 and Jones and Joshua, 1988).
The administration of calcium gluconate to treat dystocia can be directed and
tailored based on the results of monitoring. Generally, the administration of calcium
increases the strength of myometrial activity. When ineffective weak uterine contractions
are detected calcium gluconate as 10 per cent solution (0.465 mEq Ca++/ml) can be
given subcutaneously at a rate of 1 ml per 4.5 kg/10 lb body weight (Davidson, 2003a).
Calcium therapy has been shown to be useful in cases where bitches have failed to
respond initially with oxytocin alone, and is a helpful therapy in the medical management
of dystocia (Gaudet, 1985). A complicating factor is that many bitches with primary
inertia have serum calcium concentrations that are similar to those with normal
39
myometrial contractions, making diagnosis of hypocalcaemia difficult unless ionized
calcium is available diagnostically (Jackson, 1995).
Johnston, et al., (2001) compared blood calcium levels between those bitches
giving birth spontaneously and those requiring assistance and concluded that there was no
indication that blood calcium deficiency is the cause of uterine inertia in 17 of 26
animal’s diagnosed dystocia because of uterine inertia. Several salts of calcium are
commercially available, and 10 per cent calcium gluconate is commonly used in bitches
at a dose of 0.2 ml/kg body weight by I.V route or 1-5ml per kg body weight
subcutaneous route. Since cardiac arrhythmias are a potential side effect while
administering calcium intravenously care should be taken to deliver the medication
slowly, with concurrent chest auscultation.
2.11.1.3 Dextrose
Freak (1962) reported a clinical case of hypoglycemia associated with parturition
in the bitch which was first mistaken as eclampsia and only true state of affairs was
diagnosed, when there was failure to respond to calcium, but, responded to 10ml of 20
per cent glucose given intravenously.
Hypoglycemia has also been reported to cause uterine inertia during parturition
(Buckner, 1979). It has been reported that, hypoglycemia can give rise to a picture similar
to hypocalcemic in bitch and differential diagnosis between hypoglycemia and other
causes of uterine inertia requires blood sugar tests (Buckner, 1979).
40
Successful correction of uterine inertia due to hypoglycemia by intravenous
glucose administration has also been reported in bitch (Bennet, 1974; Greiner, 1974 and
Jones and Joshua 1988).
Some authors have proposed hypoglycemia as a cause of primary inertia,
especially in toy breeds of dogs (Linde-Forsberg and Eneroth, 2000). But others have
stated that hypoglycemia is uncommon in canine dystocia (Johnston, et al., 2001). One
study (Bergstrom et al., 2006) also reported that many bitches had hyperglycemia during
dystocia, and this was thought to be secondary to high cortisol concentrations, which
have been measured during normal labor in dogs (Olsson et al., 2003).
Lucio et al., (2008) reported that Bitches exhibited normal glycemia independent
of the obstetric management. In their study on peripartum hemodynamic status of bitches
under distinct obstetric conditions and also considered Labor is a stressful condition for
any female, signed by a reflex release of cortisol and relative hyperglycemia. However,
an endocrine control through an acute release of insulin maintains glucose level at the
normal range.
Bergstrom et al., (2006) in their experiment to evaluate two treatment methods in
bitches with primary uterine inertia in relation to blood concentrations of oxytocin,
calcium and glucose reported that before treatment, blood glucose values were 95.0+/-0.5
mmol/l in-group treated with combination of intravenous calcium solutions and oxytocin
and 7.3+/-1.4 mmol/l in-group treated with oxytocin only.
41
2.11.2 Digital manipulation and forceps delivery
Bennet (1974) stated that the indications for the delivery of puppies pervaginum
by digital and forceps manipulations are in (a) cases of mal-disposition amenable to
correction pervaginum, (b) cases of slight foetal oversize where, the removal of
obstructive pup may be reasonably expected to result in the normal progression of
parturition, (c) to deliver a dead obstructed foetus if it is the last remaining pup and (d) to
deliver the last remaining foetus in cases of uterine inertia. The author also states that,
simple digital delivery of the foetus should always be tried first before obstetrical
instruments used.
Gaudet (1985) while treating 116 cases of dystocia in the bitch reported that,
pervaginal manipulation was successfully employed to relieve dystocia in 12 cases.
Darvelid and Forsberg (1989) recorded that, digital manipulation including forceps
delivery was successfully employed in only 3.3 per cent of 181 cases of dystocia handled
by them.
Other less commonly reported techniques for relieving dystocia in bitch include
embryotomy (Benesch, 1952, 1956, 1958; Stein, 1954 and Gotze, 1960) and episiotomy
(Bolcshazy, 1955; Bennet, 1974 and Mosier, 1986).
2.11.3 Caesarean section
Caesarean section today has become a safe and simple technique. The indications
for it have been described by several authors (Wright, 1939; Freak, 1948; Health, 1963;
Bennet, 1974 and Mosier, 1986).
42
Freak (1962) found that, in a series of 222 cases of dystocia in bitch 50 cases
required cesarean section. In a retrospective study of 116 cases Gaudet (1985) reported
that, nearly 69 (60%) cases required cesarean section of which 29 were treated medically
also before cesarean section while the rest were directly operated upon. In a similar
retrospective study of 182 cases of canine dystocia Darveild and Forsberg (1989)
reported that, a total of 65.7 per cent of bitches with dystocia required a caesarean
section.
Moon et al., (1998) reported survival rates immediately, 2 hours, and 7 days after
delivery as 92, 87, and 80 per cent, respectively for puppies delivered by cesarean section
(n = 3,410) and 86, 83, and 75 per cent respectively for puppies born naturally (n=498).
For 614 of 807 (76%) litters, all puppies delivered by cesarean section were born live
with maternal mortality rate of 1 per cent (n = 9).
2.12 Anesthetic Protocols
Anesthesia for cesarean section should ideally provide adequate muscle
relaxation, analgesia, and narcosis or sedation for optimal operating conditions and safety
to the dam and the fetuses. Since drugs that depress the dam cross the blood-brain barrier,
it is impossible to anesthetize the dam without exposing the fetuses to the anesthetic
(Benson and Thurmon, 1984). The unique physiology of the pregnant patient guides the
clinician in selecting the most appropriate anesthetic protocol for both the dam and the
fetus. Pregnant dams have decreased lung volume, decreased functional residual capacity
and increased oxygen consumption which predisposes them to arterial hemoglobin
desaturation and lung atelectasis. Pregnant bitches also have reduced esophageal
43
sphincter tone and increased intragastric pressure, which makes regurgitation more likely.
Changes in maternal respiratory and cardiovascular physiology that occur during
pregnancy and neonatal physiology and circulation have a significant impact on
anesthetic pharmacokinetics and pharmacodynamics (Pascoe and Moon, 2001).
2.12.1 Premedication
Premedication of a painful, anxious, aggressive or furious patient may be
beneficial in decreasing the maternal stress response (elevated cortisol and catecholamine
release) and aid uterine perfusion (Paula and Peter, 1998). These stress hormones will
cause constrictions of uterine vessels and increase uterine vascular resistance.
Premedication also allows hair clipping prior to anesthetic induction and better tolerance
of the oxygen mask. With the few exceptions, the type of drug used for premedication
does not appear to affect fetal outcome, provided appropriate doses and effects on dam’s
condition are considered (Moon et al., 2000).
2.12.2 Induction and maintenance of general anesthesia using rapid acting
intravenous anesthetic agent
Propofol exists as oil at room temperature and cannot be administered
intravenously and therefore, it was initially formulated in a solubalizing agent called
polyoxyethylated castor oil (Cremaphor EL). Preliminary trials of this formulation alone
and its compatibility with other common anesthetic agents were carried out in mice, rats,
rabbits, cats, pigs, and monkeys with promising results. Propofol is a new short-acting,
intravenous anesthetic agent which has been approved for use in other countries in
humans and in dogs and cats. Propofol has proven to be a popular agent for use in day-
44
patient surgeries because of its rapid metabolism with reduced postanesthetic nausea,
thereby enabling the patient to achieve a rapid return to full activity (Glen, 1980).
Gin (1994) reported that use of Propofol as an induction and maintenance of
general anesthesia during pregnancy reduces the cardiovascular response to laryngoscopy
and tracheal intubation, marginally quicker maternal recovery from anesthesia and
satisfactory neonatal outcome.
The vehicle, however, was found to cause mild to severe histamine release, and
all anesthetic agents containing Cremaphor EL were withdrawn from use in humans.
After further research, "Intralipid," a parental nutritional agent, which contains soybean
oil, glycerol and purified egg phosphatide is now used (Glen and Hunter., 1984). Despite
the formulation is "milky" in appearance, it can still be injected intravenously. Since the
vehicle is capable of supporting bacterial growth, remaining contents of an opened
ampoule must be discarded after 6 to 12 h (Glen, 1980).
Puppy survival rate following caesarean section has been reported to be
satisfactory with the use of propofol in the anesthetic protocol (Kaneko et al., 1993).
Propofol has been used in human obstetrical practice and has the advantage of rapid onset
and short duration with minimal residual fetal depression (Siafaka et al., 1992). However,
it is stated that it should not be used without regard to the dam’s clinical condition as it
has a significant cardiopulmonary effect and need to be titrated carefully to effect (Paula
and Peter, 1998). These effects decrease the cardiac output, blood pressure and most
importantly uterine blood flow (Paula and Peter, 1998). Propofol is also reported to cause
a transient apnea and may cause severe fetal hypoxia and academia if the mother is not
45
preoxygenated, rapidly intubated and provided with enriched oxygen and assisted
ventilation. These transient effects may not be problematic in healthy patients but will
enhance fetal acidosis and hypoxia if these conditions are preexisting.
2.12.3 Induction and maintenance of general anesthesia using a combination of fast
acting intravenous anesthetic agent and dissociative anesthetic agent
When Propofol is used as the only anesthetic agent, a higher dose is required to
induce an equipotent level of CNS depression compared with the situation when dogs are
premedicated (Short and Bufalari, 1999). However, when compared to isoflurane, total
intravenous anaesthesia with propofol in pregnant bitches resulted in superior
haemodynamics (Gaynor, 1998). The dose of all induction agents and therefore their
side-effects can be reduced by first giving intravenous lidocaine (0.25-0.5 mg/kg),
diazepam (0.1-0.4 mg/kg), or midazolam (0.1-0.3 mg/kg), ketamine (4-6 mg/kg i.v.)
combined with diazepam (0.1-0.4 mg/kg i.v.) or midazolam (0.1-0.3 mg/kg i.v.).
Ketamine combinations do not affect overall puppy survival but have necessitated more
vigorous resuscitative efforts (Moon and Erb, 2002).
Lerche et al., (2000) reported that during anesthesia, the heart rate, but not the
systolic arterial pressure, was consistently higher in group which received Propofol and
ketamine at 2 mg/kg bodyweight of each intravenously (range 95 to 102 beats per
minute) than in group that received Propofol alone at 4 mg/kg bodyweight intravenously
(range 73 to 90 beats per minute). Further, post induction apnoea was more common in
group which received propofol alone but muscle twitching was observed in equal number
of dogs in both the groups and the recovery time was similar in both the groups. Propofol
46
followed by ketamine was comparable with propofol alone for the induction of
anaesthesia in healthy dogs.
Seliskar et al., 2007 evaluated the cardiorespiratory parameters, the depth of
anaesthesia and the quality of recovery in six spontaneously breathing dogs that had been
premedicated with medetomidine (40 µg/kg, supplemented with 20 µg/kg an hour later),
administered with either propofol (1 mg/kg followed by 0.15 mg/kg/minute,
intravenously), or with ketamine (1 mg/kg followed by 2 mg/kg/hour, intravenously) and
propofol (0.5 mg/kg followed by 0.075 mg/kg/minute, intravenously) and they reported
that the dogs' heart rate and mean arterial blood pressure are higher and their minute
volume of respiration and temperature are lower when they were anaesthetised with
propofol plus ketamine, and a progressive hypercapnia leading to pronounced respiratory
acidosis and the Propofol-Ketamine anaesthetized dogs recovered more quickly but
suffered some unwanted side effects, the dogs which were anaesthetized with propofol
alone recovered more slowly but uneventfully (Seliskar et al., 2007).
Tatiana et al., (2007), opined that haemodynamic values were stable in dogs
received propofol with ketamine and propofol with racemic ketamine for induction and
maintenance of anaesthesia. However, an intense respiratory depression was also
observed. The combination of propofol with ketamine showed better recovery, probably
due to lower dose requirements and also they opined that, further studies are necessary to
evaluate different approaches in order to establish new protocols regarding the combine
use of propofol and ketamine.
47
2.12.4 Induction and maintenance of general anesthesia using an inhalant
anesthetic agent
Although all inhalant anesthetics have been used successfully for canine cesarean
section, methoxyflurane was associated with decreased puppy survival rate. Isoflurane
has been reported to result in a better puppy survival rate when used as an inhalant
anesthetic for cesarean section in bitches (Kaniko et al., 1993).
Halothane did not have any positive or negative effect on cesarean born puppies
and Isoflurane was associated with improved neonatal survival. In healthy women,
neonates are also unaffected by halothane as long as induction-delivery interval was short
but when fetal distress was present, halothane aggrevated the condition. (Moon et
al.,1998).
2.13 Epidural Analgesia for cesarean section
Local anaesthetic techniques, epidural or spinal anaesthesia using local
anaesthetic agents with or without an opioid may be used as the sole technique for
surgery. These techniques produce minimal foetal depression. However, local
anaesthetics placed in the epidural or subarachnoid space produce systemic
vasodilation and hypotension (Chan et al., 1997). The ideal patient for this technique
is the healthy bitch, but in practice few patients will tolerate being placed in
dorsal recumbency while fully conscious. Debilitated and exhausted dams that may
tolerate this technique can become severely hypotensive because of pre-existing
hypovolemia. In a non-pregnant animal 1.00 ml of 2 per cent lidocaine per 5 kg of
body weight deposited epidurally will produce a block up to the level of L2 (Skarda.,
48
1996). In the pregnant animal, this dose may produce a higher block because of
distended epidural veins, a consequence of increased intra-abdominal pressure,
decrease the epidural space. A danger of this technique is that the airway is not
protected and regurgitation and vomiting are possible when the bitch is placed in
dorsal recumbency.
Epidural anesthesia is the chemical blocking of function of the nerves that supply
the back part of the patient. Administration of 1 ml/6 kg body weight of 2 per cent
lidocaine (approximately 3 mg/kg) is sufficient for performing cesarean section. This
technique dilates the blood vessels in the anesthetized portions of the patient. The vessel
dilatation decreases blood pressure. It is therefore, necessary to put the patient on
intravenous fluids to maintain blood volume during surgery. There is minimal fetal
exposure to anesthetics and pups are more vigorous at birth. Epidural anesthesia for
cesarean section is a safe alternative to systemic anesthesia. An excitable bitch is not a
good candidate for cesarean section under epidural analgesia (Wetmore and Glowaski,
1999).
2.14 Evaluation of anesthesia
Fetal depression following dystocia and Cesarean section has two primary causes;
the first and often most important cause is hypoxia and the second is depression from
anesthetic agents given to the dam (Traas., 2008). Neonatal survival is also influenced by
adequate support of the puppy upon delivery. Resuscitation efforts should be provided in
the following order: warmth, airway, breathing, circulation, and drugs. The airway should
49
be immediately cleared by wiping away the fluid and membrane around the muzzle using
a clean, dry towel while holding the neonate on in a head downward position.
Mason (2006) reported that puppy vigor at the time of delivery is most impaired
by anaesthetic techniques that include Ketamine and may increase uterine tone and as a
result diminish uterine blood flow nearing the time of delivery.
Based on number of surveys the mortality of puppies upto weaning age appear to
range between 10 and 30 per cent and averages around 12 per cent in dogs (Linde –
Forsberg and Forsberg, 1983). More than 65 per cent puppy mortality occurs at
parturition and during the first week of life and very few puppies die after 3 week of age.
Immediate survival rate of puppies delivered by Cesarean-section is reported as
92 per cent falling to 87 per cent and 80 per cent at two hours and 7 days respectively
(Moon and Erb, 1998; Moon and Erb., 2000). The puppy survival is much improved
compared to reports of the 1960’s when mortality rates were as high as 36 per cent
(Mitchell., 1966). Mortality rates for bitches undergoing cesarean section dropped
from approximately 13 per cent (Mitchell., 1966) to 1 per cent (Moon et at., 1998;
Moon and Erb., 2000) over the past 40 years. Over half of canine cesarean sections are
emergency procedures (Moon and Erb, 1998) and puppy mortality is 12.7 per cent in an
emergency situation compared to 3.6 per cent when elective. When labour is prolonged,
dehydration, hypovolemia, sepsis, stress, exhaustion, and hypocalcaemia may be present
leading to worst outcomes. Elective procedures should be considered in Bulldogs which
constitute 17 per cent of all cesarean sections (Moon et at., 2000).
50
Significant canine neonatal mortality rates are reported regardless of the
intervention provided. A large multicenter prospective study to examine cesarean section
mortality rates are conducted with 3,908 puppies delivered from 808 dams. Puppies
delivered by cesarean section had mortality rates of 8 per cent at birth, 13 per cent 2
hours later, and 20 per cent at 7 days after parturition. Puppies born vaginally during
dystocia had mortality rates of 14 per cent, 17 per cent, and 25 per cent, respectively, at
the same time intervals mentioned above. Funkquist et al., (1997) reported similar
neonatal survival data after cesarean section but also identified a significant increase in
mortality when some puppies had been born vaginally before cesarean section. This
finding supports retrospective data that identified increased puppy mortality when stage 2
labor was prolonged and is in agreement with the cited overall dystocia puppy mortality
rate of 22 per cent. Maternal mortality rates were reported to be 1 per cent even after 58
per cent of the cesarean sections performed were on emergency basis.
Materials and Methods
III. MATERIALS AND METHODS
3.1 Factors influencing dystocia in dog
The influence of breed, size, age and parity of the dam on the incidence of
dystocia in bitches was studied by analyzing the medical records of dystocia cases
presented at the department of Gynaecology and Obstetrics, Veterinary College, Hebbal,
Bangalore between January 1997 to March 2009 as well as from the data generated from
clinical cases of dystocia handled during the course of present study, (January 2008 and
May 2009). A detailed proforma regarding different parameters considered for the
present investigation was prepared (Annexure I) and the data was transferred into a
proforma for the purpose of analysis.
3.1.1 Breed
The pooled data generated from the clinical records of dystocia cases treated
retrospectively as well as dystocia cases treated during the course of the present
investigation was analyzed to study the influence of the breed of the bitch on the
incidence of dystocia.
3.1.2 Age
The age of the bitch at the time of the presentation with the complaint of dystocia
was obtained from each case record as well as from the clinical cases handled during the
course of investigation. The animals were grouped into less than 2 years, 2 to 4 years, 4
to 6 years, 6 to 8 years and more than 8 years. The frequency distribution of dystocia in
52
different age groups was compared to assess the possibility of predisposition of age of the
animal to dystocia.
3.1.3 Size
Based on the recommended body weights of the breed of the animal, patients with
dystocia were categorized into the following groups in an attempt to asses the
relationship of the size of the animal with the incidence of dystocia
a. Small sized breeds (body weight less than 10 kgs)
b. Medium sized breeds (body weight between 10-25kgs)
c. Large sized breeds (body weight between 25-45 kgs) and
d. Giant sized breeds (body weight more than 45 kgs)
3.1.4 Parity
Data regarding the parity of the animal was obtained to compare variation, if any
in the incidence of dystocia between primiparous and pluriparous animals.
3.1.5. Gestation period
Gestation period calculated as the interval from the day of first mating to the day
of onset of parturient symptoms recorded in each bitch presented with history of dystocia
in both retrospective study cases as well as from clinical cases presented during the
course of the present investigation was utilized to assess the effect of the length of
gestation period on incidence of dystocia.
53
3.2 Obstetrical history
The information regarding the behavioral signs exhibited by the bitches with
dystocia and the interval from the time of onset of labour to the time of presentation to
the obstetrical clinic were obtained only from clinical cases of dystocia handled during
the course of present investigation as this information was not available in many of the
clinical records of the cases treated earlier.
3.2.1 Behavioral signs exhibited by the bitches with dystocia
In clinical cases of dystocia presented during the course of the present
investigation, the owners were specifically questioned about the behavioral signs
exhibited by the bitch such as restlessness, anorexia, panting, nesting and vomiting.
3.2.2 Interval from onset of labour to its referral
The information regarding the approximate duration of dystocia was obtained in
clinical cases of dystocia presented during the course of present investigation and based
on the interval from the onset of labour to its referral, the animals were classified into,
A. Animals presented with the history of greenish/blackish green vaginal discharges
for the past one to two hours without the expulsion of any of the fetuses (primary
uterine inertia)
B. Animals presented with the history of greenish/blackish green vaginal discharges
for the past two to six hours without the expulsion of any of the fetuses (primary
uterine inertia).
54
C. Animals presented with the history of greenish/blackish green vaginal discharges
for more than six hours without the expulsion of any of the fetuses (primary
uterine inertia).
D. Animals presented between four and eight hours after the delivery of one or more
puppies normally and subsequently showing weak or complete absence of clinical
evidence of labor pains (partial primary uterine inertia).
E. Animals presented beyond eight hours after the delivery of one or more puppies
normally and subsequently showing either weak or complete absence of clinical
evidence of labor pains (partial primary uterine inertia).
F. Animals presented within one hour after the onset of strong and frequent
abdominal straining that failed to deliver a puppy (Obstructive dystocia).
G. Animal presented between one to four hours after the onset of strong and frequent
abdominal straining that failed to deliver a puppy (Obstructive dystocia).
H. Animals presented beyond four hours after the onset of strong and frequent
abdominal straining that failed to deliver a puppy.
3.3 Clinical examination
The clinical examination included the ultrasonographic measurements of the fetal
head to record the gestational age, assessment of temperature, pulse and respiration,
recording the nature of discharges in bitches with dystocia and a detailed vaginal
examination to identify the cause of dystocia. These observations were carried out only
on patients handled during the course of the present investigation.
55
3.3.1 Gestation period calculated based on ultrasonographic measurements on the
fetus
Patients with dystocia were subjected to ultrasonography using a 5 to 7.5 MHz
trans- abdominal probe (HONDA ELECTRONICS, HS-2000). The ultrasonographic
instrument used in the present study has been specifically designed for veterinary
obstetrical use and has been pre-calibrated to provide the gestational age on the basis of
the measurements of the fetal head diameter. The age of gestation is displayed in days as
calculated from the day of LH surge during estrus.
Briefly, the procedure employed for ultrasonic measurements of the fetal head
diameter was as follows. The hair on the ventral abdomen between xiphi sternum and
pubis and extending to several centimeters on either side of the midline was clipped and
ultrasonography was carried with the patient in dorsal recumbency. After application of
coupling gel to improve the contact, the sector probe was placed on the posterior
abdomen and slowly moved anteriorly and laterally until the fetal head was clearly
visible. The image was frozen and the fetal head diameter was measured. The
measurements were then fed to the instrument which in turn gave the gestational age in
days from the day of LH surge. The procedure was repeated on two other fetuses to
obtain head diameter and the average gestation period was calculated.
3.3.2 Temperature, Pulse and Respiration
The temperature was recorded in Fahrenheit using a digital clinical thermometer.
The pulse and the respiratory rate were recorded as number per minute.
56
3.3.3 Nature of discharges in bitches with dystocia
The nature of discharge exhibited by patients with dystocia was recorded by
obtaining the history from the owner, visual inspection of the perineum and vulva and
Endoscopic examination of the vaginal lumen which was carried out using a rigid
fibroptic vaginal endoscope (STORZ, KARL STORZ-ENDOSCOPY). The endoscopy
also enabled the presence or absence of water bag in the vaginal lumen which could not
be identified by digital examination of the vagina and the patency of the cervix.
Based on the nature of vaginal discharges, animals with dystocia were categorized into,
a. Animals exhibiting no vaginal discharges.
b. Animals exhibiting greenish/blackish green vaginal discharges.
c. Animals exhibiting hemorrhagic vaginal discharges.
d. Animals exhibiting foul smelling brownish discharges.
3.4 Causes of dystocia
Every clinical case of dystocia presented during the course of present
investigation was subjected to the following procedures to identify the cause of dystocia.
a. Trans-abdominal ultrasonographic examination to identify the approximate
fetal number, fetal viability and fetal head abnormalities.
b. Gloved finger examination of the vagina to identify the abnormalities of the
vagina such as vagino-vestibular constrictions, presence of vaginal
bands/septum, pelvic bone abnormalities, narrow pelvic inlet, tumors of the
vagina and the presentation, position and posture of the fetus.
57
c. Endoscopic examination of the vagina to identify vaginal abnormalities,
presence of allanto-chorionic sac, nature of vaginal discharges and degree of
dilation of cervix.
The clinical history obtained from the owner was correlated with the clinical
findings of abdominal ultrasonography, gloved finger examination of the vagina and
endoscopic examination and a final diagnosis with regard to the cause of dystocia was
made. The cause of dystocia was further categorized broadly into either maternal or fetal
in origin (Arthur et al., 1989). An attempt was also made to analyze the various causes of
maternal and fetal dystocia in bitches. In addition, the relationship of the age, size and
parity of bitch with the various forms of maternal and fetal dystocia were also studied.
3.5 Evaluation of treatment procedures
The selection of treatment procedure employed was primarily based on the cause
of dystocia and one of the following treatment protocols was employed to relieve
dystocia.
a. Medical management
b. Vaginal manipulation
c. Caesarean section
3.5.1 Medical treatment
Medical treatment was carried out only in those cases of dystocia where the cause
was diagnosed either as primary uterine inertia or partial primary uterine inertia. The
medical treatment consisted of intravenous administration of 25 per cent Dextrose,
58
oxytocin at the rate of 0.1 IU per kg body weight intravenously and intravenous
administration of 10 per cent calcium gluconate at the rate of 0.5 ml per kg body weight
but not exceeding a total dose of 10 ml. Oxytocin was administered for a maximum of
three injections, the interval between injections being not less than 30 minutes. Calcium
gluconate was administered only once. Animals failing to respond to medical treatment
were immediately subjected for caesarean section.
3.5.2 Vaginal manipulative procedures
Vaginal manipulative procedures were adopted in cases of dystocia diagnosed to
have been caused by presentation, position and postural abnormalities of the fetus or
structural abnormalities of the reproductive tract interfering with the normal passage of
the fetus such as bands of septum in the vagina or an incompletely relaxed vagina and
vulva. The vaginal manipulation was carried out following all aseptic precautions and
using either a gloved finger or a vaginal sponge forceps. Cases of dystocia which could
not be relieved through vaginal manipulative procedures were immediately subjected for
caesarean section.
3.5.3 Caesarean section
Caesarean section as the first line of treatment was carried out in those cases of
dystocia caused by pelvic bone abnormalities or complete primary uterine inertia which
in the opinion of the obstetrician does not respond to conventional medical treatment. It
was also the only line of treatment carried out in protracted cases of dystocia
characterized by fetal death and emphysema and maternal septicemia. Caesarean section
59
was also carried out on those cases which failed to respond to medical treatment or
vaginal manipulative procedures.
Before subjecting the animals for surgery, they were again subjected to
ultrasonographic evaluation for determining the fetal viability. The fetal viability was
assessed on the basis of the presence or absence of the heart beats and observations for
fetal movements.
3.6 Evaluation of anesthetic protocols for cesarean section
Although, cesarean section was carried out in all those cases failing to respond to
medical therapy or vaginal manipulative procedures, the evaluation of various anesthetic
protocols for cesarean section was carried out only in those bitches where there was
ultrasonographic evidence of viability of all the fetuses prior to surgery. Animals with
dead fetuses or those with both dead and live fetuses were also subjected to cesarean
section, but were not included for further evaluation and were excluded from the present
study.
3.6.1 Hematological and Blood biochemical studies in animals subjected for
cesarean section
Blood samples were obtained from every animal subjected for cesarean section in
order to establish the hematological and biochemical changes if any in patients with
dystocia. Blood samples were obtained once prior to premedication and again after the
completion of the surgery. Blood samples were also obtained from six other animals just
prior to onset of parturition and again after the completion of normal process of delivery
60
(control group). The hematological and biochemical parameters were recorded using
SYSMEX model pocH-100i and BIOSYSTEMS A15 respectively. The hematological
parameters studied were (a) Total leukocyte count (cells/cmm), (b) Hemoglobin (g/dl)
and (c) Platelet count (Lakhs/dl).
The blood biochemical parameters studied were (a) Blood Urea Nitrogen (gms %)
(b). Serum Creatinine (gms %) (c). Alanine amino transferase (SGPT) (U/l) (d). Random
Blood sugar (gms %) and (e) Serum Calcium (mg/dl).
3.7 Electrocardiography
Electrocardiographic studies were carried out in animals selected to undergo
cesarean section to evaluate cardiac changes if any. Electrocardiographic examination
was carried out subjecting the animal to the least possible stress using a four lead
electroradiogaphic machine (CARDIART 6108t, BPL). The interpretation of
electrocardiograph was made by a Veterinary Physician specialized in canine cardiology
3.8 Preparation of the patient and premedication
Cesarean sections were carried out in 48 animals with viable fetuses through a
mid-ventral incision which was aseptically prepared for surgery. The drugs used for
premedication consisted of diazepam (0.5 mg per kg weight, IV) and atropine sulphate
(0.04 mg per kg body weight, IM) which were administered about 10 minutes prior to
surgery. During this period as well as during and after the entire surgical procedure, the
animals were constantly infused with a balanced electrolyte solution (Ringer’s solution)
in an attempt to correct hypotension and maintain hydration status. Following
61
premedication, the time of onset of sedation based on drooping of the eyelids, head down
and attainment of recumbency were recorded.
3.9 Anesthetic protocols
The animals which were subjected to premedication as described above were
randomly allotted to three general anesthetic protocols with each group comprising of 12
animals. In addition, another group of 12 animals premedicated similarly were subjected
to cesarean section under epidural analgesia.
3.9.1 Group I: Rapid acting intravenous anesthetic agent
The general anaesthesia was induced and maintained in 12 animals with dystocia
by administrating the anaesthetic agent, intravenously. The anaesthetic agent (propofol)
was administered initially at a dose rate of 5-10mg/kg body weight to effect general
anaesthesia as evidenced by the absence of pedal reflexes, palpebral reflexes and ventro-
medial deviation of the eyeball (third stage of anesthesia). Subsequently, Propofol was
administered intermittently as and when needed to maintain general anaesthesia.
3.9.2 Group II: Combination of fast acting intravenous anaesthetic agent and
dissociative anaesthetic agent
In another group of 12 patients with dystocia the general anaesthesia was induced
and maintained using a combination of fast acting IV anaesthetic agent (Propofol) and
dissociative anaesthetic agent (ketamine). The anesthetic agents propofol and ketamine
were drawn into the same syringe in ratio of 1:1 (V/V) and administered i.v to effect
general anaesthesia as judged by the signs of third stage of anaesthesia.
62
3.9.3 Group III: Inhalant anaesthesia agent
In 12 animals with dystocia, cesarean section was carried out under general
anaesthesia using Isoflurane (FORANE , Abbott Laboratories Ltd., England) an inhalant
anaesthetic agent. Isoflurane was administered through a face mask using a Boyle’s
anesthetic apparatus initially at the rate of 3-5 per cent administered until the animal
attained the third stage of anesthesia. Simultaneously, oxygen was also infused at the rate
of 1.5 per cent. Once the animal attained third stage of anesthesia, animals were
maintained in the third stage using Isoflurane at 1 per cent concentration and oxygen at
1.5 per cent concentration.
3.9.4 Group IV: Epidural analgesia for cesarean section
A group of 12 animals with dystocia were subjected to cesarean section using
epidural analgesia. Epidural anesthesia was induced by injecting 2 per cent Lignocaine
hydrochloride solution at the rate of 1 ml per 3 kg body weight. Briefly, the technique of
epidural anesthesia carried out was as follows.
The site for needle placement was clipped and prepared in a sterile manner similar
for surgery. Sterile gloves were worn for the procedure. A spinal needle with a stylet of
about 22–20 g x 1½”–2½” in length placed exactly on midline in the center of the hollow
palpated between the dorsal spinal processes of L7 and S1. A “pop” could be felt as the
needle traverse through the tough interspinous ligament and into the much less resistant
epidural space. A sterile syringe containing air was connected to the spinal needle and a
small amount of air was injected. After verification of the position of the needle, the
63
syringe containing the analgesic agent was connected and the agent was injected slowly.
The needle was withdrawn completely after the agent was administered.
3.10 Evaluation of anesthesia
In every anesthetic protocol used, the following parameters were recorded in an
attempt to compare the effects of the anesthetic protocol on the dam and the neonates.
The duration of surgical anesthesia and complications of anesthetic procedure observed if
any
a. Time taken for induction of general anesthesia.
b. The ease of induction of anaesthesia and the degree of skeletal muscle relaxation.
c. Time taken by the dam to exhibit the first sign of recovery from anesthesia after
the completion of surgical procedure and discontinuation of administration of
anaesthetic agent.
d. The degree of cardiovascular and respiratory depression of the neonate with
various anesthetic protocols.
e. Percentage of viable fetuses delivered with each anesthetic protocol.
3.11 Statistical analysis
Wherever deemed necessary, the data generated from the present investigation
were subjected to chi-square test, as per the procedures described by Snedecor and
Cochran (1996) to study the variations in the frequency of dystocia.
Results
IV RESULTS
A retrospective analysis of clinical records maintained in the department of
Gynecology and Obstetrics, Veterinary College, Bangalore revealed that a total of 996
dystocia cases were referred for treatment between January 1999 and March 2009. In
addition, 240 more cases of dystocias were treated during the course of the present
investigation (January 2008 to May 2009). Thus, in all 1236 cases of canine dystocias
were analyzed to determine the influence of various factors on the frequency distribution
of dystocias, etiology and line of treatment.
4.1 Breed wise distribution of dystocia treated
The frequency distribution of the incidence of dystocia in different breeds out of
the total animals treated is presented in Table 1. Dystocia was encountered in 18 different
breeds. Among different breeds, the highest frequency was recorded in Labrador
Retriever (18.12%) followed by German Shepherd (12.00 %), Boxer (9.40%), Pug
(9.06%) and Dachshund (8.40 %). The incidence of dystocia was least in Basset Hound
(1.30 %). The Chi-square analysis revealed a significant (P<0.05) variation in the
breedwise number of cases treated for dystocia.
4.2 Size wise distribution of canine dystocia treated in dogs
Influence of size of breed on the frequency distribution of dystocia treated is
presented in Table 2. Among 1236 cases of dystocias analyzed in the present study, 422
cases were in large sized breeds (34.14 %), 360 cases were in small sized breeds (29.12
%). The number of animals with dystocia in medium and giant sized breeds were 228
65
(18.44 %) and 226 (18.28 %) respectively. The Chi-square analysis revealed a significant
(P<0.05) effect of size of breed of the bitch on the frequency distribution of dystocia
cases treated.
4.3 Agewise distribution of canine dystocia treated
The frequency distribution of dystocia in different age groups treated is presented
in Table 3. The highest number of dystocia was encountered in animals aged 2-4 years
(32.36 %) and was least in bitches aged over 8 years (11.18 %). The incidence of
dystocia in bitches aged less than 2 years, 4-6 years and 6-8 years were 24.75, 17.96 and
13.75 per cent respectively. Chi-square analysis revealed a significant (P≤0.05) effect of
age of the bitch on the frequency distribution of dystocia in canines.
4.4 Paritywise distribution of canine dystocia treated
The effect of parity of the bitch on the frequency of dystocia treated is presented
in Table 4. The highest number (31.07%) of dystocias treated was in first parity bitches.
Further, among pluriparous animals, the incidence of dystocia was slightly higher during
second and third delivery (27.02 %) as compared to the incidence during fourth and fifth
delivery (22.98 %). The incidence of dystocia was comparatively lower after fifth
delivery (18.93 %). Chi-square analysis revealed a significant (P≤0.05) effect of parity of
the bitch on the frequency distribution of dystocia in canines with highest incidence in
primiparous.
66
Table 1. Breedwise distribution of canine dystocia cases treated (N=1236)
Breed Number of cases of dystocias
Incidence (%)
Basset Hound 16 1.30 Beagle 32 2.60 Boxer 116 9.40 Bull dog 64 5.17 Cocker spaniel 56 4.53 Dachshund 104 8.40 Dalmatian 36 2.91 Doberman 56 4.53 German shepherd dog 148 12.00 Golden retriever 36 3.00 Great Dane 56 4.53 Labrador retriever 224 18.12 Lhasa apso 28 2.26 Mastiff 24 1.94 Mongrels 52 4.20 Pomeranian 52 4.20 Pug 112 9.06 St.bernard 24 1.94 Total 1236 100.00
*(P<0.05)
Table 2. Size wise distribution of canine dystocia cases treated (N=618)
Size of breed Number of cases of dystocias Incidence (%)
Small (BW < 10 Kg) 360 29.12 Medium (BW 10-25 kg) 228 18.44 Large (BW 25 TO 45 Kg) 422 34.14 Giant (BW 45Kg and above) 226 18.28 Total 1236 100.00
*(P<0.05)
67
Table 3. Age wise distribution of canine dystocia cases treated (N=618)
Age (years) Number of cases of dystocias Incidence (%)
< 2 306 24.75
2-4 400 32.36
4-6 222 17.96
6-8 170 13.75
> 8 138 11.18
Total 1236 100.00
*(P<0.05)
Table 4. Parity wise distribution of canine dystocia cases treated (N=618)
Parity Number of cases of dystocias Incidence (%)
1st 384 31.07
2-3 334 27.02
4-5 284 22.98
>5 234 18.93
Total 1236 100.00
*(P<0.05) Significant at 5 % level
68
4.5 Frequency distribution of dystocias in bitch based on gestational age based on
mating date
The gestational age ranged from 57-70 days with a mean of 62.16±3.95 days. The
per centage of animals with an apparent gestation period of 57 to 62, 62 to 65 and 65 to
70 days and were treated for dystocia 43.33, 33.34 and 23.33per cent respectively.
4.6 Gestational age in bitches with dystocia as assessed by the Ultrasonography
The mean gestational age in 240 bitches with dystocia as assessed by
ultrasonographic measurement of fetal head diameter recorded was 61.87±3.41days and
ranged between 59-68 days.
4.7 Signs of parturition in bitches with dystocia
The parturient signs observed by the owner were analyzed in 240 cases of
dystocias presented during the course of the present investigation as this information was
not available in clinical records of dystocia cases handled earlier. The most common
parturient sign reported by the owners was excessive nesting behavior and was observed
in 30.83 per cent of animals (Table 5). The other common signs observed were
restlessness in 29.16 per cent, panting in 20.00 per cent vomiting in 10.00 per cent and
anorexia in 10.00 per cent of the animals presented for treatment. The chi-square analysis
revealed a significant (P≤0.05) variation in the incidence of different behavioral signs in
the parturient animals.
69
Table 5. Behavioral signs observed by owners in bitches with dystocia (N=240)
Behavioral signs observed No of cases Per centage
Restlessness 70 29.16
Anorexia 24 10.00
Panting 48 20.00
Nesting 74 30.83
Vomiting 24 10.00
Total 240 100.00
*(P<0.05)
70
4.8 Interval from onset of labour to presentaton for treatment.
The interval from onset of labor to the time of referral of the dystocia case for
treatment was recorded in 240 cases handled during the course of the present
investigation and the same has been presented in Table 6. A total of 72 animals were
presented with the history of blackish green/greenish discharge from the vagina without
further progress of labor. Among these animals, eight had the history of discharges for
the past 1-2 hours while four other animals exhibited the vaginal discharges for 2-6 hours
duration. A majority of the cases presented (60) however, had vaginal discharge for a
minimum of six hours without the delivery of any puppy. All these cases were
categorized as cases of primary uterine inertia.
Another 84 animals were presented with the history of delivery of one or more
puppies normally but, subsequently the labor signs had ceased in spite of the presence of
the fetuses in the uterus. These cases were categorized as cases of partial primary uterine
inertia and 36 of such cases were presented between four to eight hours after the delivery
of the preceding pup and the rest (48) after more than eight hours.
Further, 84 other animals were presented with the history of failure of expulsion
of the puppy in spite of the presence of strong abdominal contractions. These cases were
categorized as cases of obstructive dystocia which was confirmed on digital vaginal
examination. Four animals had a history of obstructive dystocia for the past 1hr, 12
animals for 1-4 hours while the rest were in labor for more than 4 hours (Table 6).
71
Table 6. Interval from onset of labour to referral in different types of dystocia
(N=240)
Duration and type of dystocia No of animals Percentage
Primary uterine inertia of 1-2hrs 08 3.33
Primary uterine inertia of 2-6 hrs 04 1.67
Primary uterine inertia of more than 6 hrs 60 25.00
Partial primary uterine inertia of 4-8 hrs 36 15.00
Partial primary uterine inertia of more than 8 hrs 48 20.00
Obstructive dystocia of less than 1-hrs 04 1.67
Obstructive dystocia of 1-4 hrs 12 5.00
Obstructive dystocia of more than 4 hrs 68 28.33
Total 240 100.00
*(P<0.05)
72
4.9 Temperature, Pulse and Respiratory rates in bitches with dystocias.
In 240 bitches with dystocia, the rectal temperature was recorded on presentation
and it was found to range from 97.6 to 104o F with a mean of 101.84±0.64o F (Table 7).
The pulse rate ranged from 53-125 per minute and averaged 84.92±2.27 (Table 9). The
respiratory rate varied from 20-99 per minute with a mean of 48.19±2.81 (Table 7).
4.10 Nature of vaginal discharges in bitches with dystocia.
Out of 240 bitches with dystocia presented during the present investigation, 117
(48.75 %) bitches showed mucoid, copious and slightly greenish tinged discharge. The
discharge was thick dark greenish/blackish green in 37 (15.42%), hemorrhagic in 06
(2.5%) and brownish and foul smelling in 80 (33.33%) animals (Table 8).
4.11 Incidence of maternal and fetal dystocia in bitches
Table 9 presents the incidence of maternal and fetal dystocia in 240 cases of
dystocia handled during the course of present investigation. The incidence of maternal
dystocia was significantly higher (63.34%) as compared to fetal dystocia (36.66%).
4.12 Incidence of various types of maternal dystocias in bitches
The primary uterine inertia was diagnosed to be the most frequent cause of
maternal dystocia and it was observed in 63.15 per cent of maternal dystocias (Table 10).
The next most frequent cause recorded was primary partial uterine inertia (28.95%). The
other causes like uterine torsion (3.94%), Pelvic bone abnormalities (1.32%) and
abnormalities of the vagina (2.64%) as causes of maternal dystocia were encountered
infrequently.
73
Table 7. Mean temperature, heart, pulse and respiration rates in bitches with
dystocias
(N=240)
Temperature (o F)
Heart (per minute)
Pulse (per minute)
Respiration (per minute)
Range 97.6-104 76-112 53-125 20-99
Mean 101.84 89.85 84.92 48.19
SE 0.636 2.423 2.272 2.812
Tabe 8. Nature of vaginal discharges in bitches with dystocia (N=240)
Nature of vaginal discharge No of animals Percentage
Mucoid, copious and slightly greenish tinged 117 48.75
Thick dark greenish/blackish green 37 15.42
Hemorrhagic 6 2.5
Brownish and foul smelling 80 33.33
Total 240 100.00
Table 9. Incidence of maternal and fetal dystocia (N=240)
Type of dystocia Nos Percentage
Maternal 152 63.34
Fetal 88 36.66
Total 240 100.00
*(P<0.05)
74
Table 10. Incidence of different maternal dystocias in bitches (N=152)
Cause Number of cases of dystocias encountered
Percentage incidence
Primary Uterine Inertia 96 63.15
Primary partial Uterine Inertia 44 28.95
Uterine torsion 06 3.94
Pelvic bone abnormalities 02 1.32
Abnormalities of the Vagina (Vaginal Septum, Constriction etc.)
04 2.64
Total 152 100.00
75
4.13 Factors influencing different types of maternal dystocia
4.13.1 Age
The chi-square analysis revealed that the age had significant influence on the
occurrence of primary complete uterine inertia as compared to primary partial uterine inertia.
The incidence of primary complete uterine inertia was highest (27.08%) in animals aged less
than 2 years. This was followed by an incidence of 22.9 % in animals in the age group of 2-4
years, and the least incidence was observed in animals in the age group of 6-8 years (10.41%)
(Table11).
The highest per centage of primary partial uterine inertia was recorded in the age
group of more than 8 years (31.81 %) followed by 27.27 per cent in the age group of 4-6.
The incidence of primary partial uterine inertia was similar in animals aged 2-4 years and
in those under two years (Table 11).
As the incidence of uterine torsion and pelvic bone/vaginal abnormalities as a
cause of maternal dystocia were encountered in a very few animals, the relationship
between age of the dam with these causes of dystocia could not be studied (Table 11).
4.13.2 Size
The study also revealed a higher frequency of occurrence of primary complete
uterine inertia in small sized breeds, the incidence being as high as 33.33 per cent. The
incidence of primary complete uterine inertia was 27.08 per cent in medium sized breeds,
followed by 20.08 per cent in giant sized breeds and was least (18.75%) in large sized
breeds (Table 12).
76
Table 11. Incidence of maternal dystocias in different age groups of bitch (N=152).
Cause of Dystocia
Age in years
Total< 2 2-4 4-6 6-8 > 8
No. of cases (percentage)
Primary complete uterine inertia
26 (27.08)
22 (22.90)
18 (18.75)
10 (10.41)
20 (20.08) 96
Primary partial uterine inertia 8 (18.18)
8 (18.18)
12 (27.27)
2 (4.54)
14 (31.81) 44
Uterine torsion 0 2 (33.33)
4 (66.66) 0 0 06
Vaginal septum 2 (50.00)
2 (50.00) 0 0 0 04
Pelvic bone abnormalities 0 2 (100) 0 0 0 02
Overall 36 36 34 12 34 152 *(P<0.05)
Table 12. Incidence of maternal dystocia in different size bitches (N=152)
Causes of dystocia Size of the bitch
Total Small Medium Large Giant
Complete Primary Uterine Inertia 32 (33.33)
26 (27.08)
18 (18.75)
20 (20.08) 96
Primary partial Uterine Inertia 12 (27.27)
6 (13.63)
24 (54.54)
2 (4.54) 44
Uterine torsion 2 (33.33) 0 4
(66.66) 0 06
Pelvic bone abnormalities 0 2 (100) 0 0 02
Abnormalities of the Vagina (Vaginal Septum, Constriction etc.) 0 4
(100) 0 0 04
Overall 46 38 46 22 152
*(P<0.05)
77
The incidence of primary partial uterine inertia on the other hand was
significantly higher in large breeds (54.54%) and small (27.27%) The incidences in
medium and giant breeds were 13.63 per cent and 4.54 per cent respectively (Table 12).
The effect of the size of the breed on the incidence of uterine torsion and pelvic
and vaginal abnormalities as a cause of maternal dystocia could not be studied due to
their low incidence encountered during the course of present investigation (Table 12).
4.13.3. Parity
The incidence of complete primary uterine inertia was significantly higher in
primiparous animals (45.83%).The incidence of partial primary uterine inertia on the
other hand was much more common in pluriparous animals (77.27%) (Table 13).
4.14 Fetal causes of dystocia
Among the total 240 cases of dystocia cases treated in the prospective study of the
present investigation 88 cases were diagnosed as fetal dystocias. Out of these fetal
dystocias 54.54 per cent were due to postural abnormalities of head which included 18.18
per cent lateral deviation and 36.36 per cent ventral flexion. The incidence of the
dystocias due to postural abnormalities of the limbs was 36.36 per cent in which highest
incidence of 22.73 per cent was because of unilateral/bilateral fore limb flexion and
dystocias due to unilateral/bilateral hind limb flexion was observed in 13.63 per cent of
animals. Dystocias due to pathological fetal oversize was seen in 9.10 per cent of the
cases presented during the course of investigation (Table 14).
78
Table 13. Incidence of maternal dystocia in different parity bitches (N=152).
Causes of Dystocia No of parity
Total First 2-3 4-5 >5
Complete Primary Uterine Inertia 44 (45.83)
16 (16.66)
24 (25.00)
12 (12.50) 96
Primary partial Uterine Inertia 10 (22.72)
22 (50.00)
12 (27.27) 0 44
Uterine torsion 0 2 (33.33)
4 (66.66) 0 6
Pelvic bone abnormalities 2 (100.00) 0 0 2
Abnormalities of the Vagina (Vaginal Septum, Constriction etc.)
4 (100.00) 0 0 0 4
Overall 60 40 40 12 152
*(P<0.05)
Table 14. Incidence of different fetal dystocias in bitches (N=88)
Cause Number of cases of dystocias encountered
Incidence (%)
1. Postural abnormalities of the head
a. Lateral flexion 16 18.18
b. Ventral flexion 32 36.36
2. Postural abnormalities of the limbs
a. Unilateral/bilateral fore limb flexion 20 22.73
b. Unilateral/Bilateral hind limb flexion 12 13.63
3. Pathological Fetal oversize 8 9.10
Total 88 100.00
79
4.13 Evaluation of treatment procedures
4.15.1 Medical treatment
The efficacy of medical treatment for relieving dystocia in bitch was evaluated in
104 bitches wherein the cause of dystocia was either primary uterine inertia or primary
partial uterine inertia. The drugs used to augment uterine contractions consisted of
oxytocin and calcium besides injecting dextrose as a source of energy. Medical treatment
adopted was successful in relieving 38.46 per cent maternal dystocia characterized by
primary uterine inertia or primary partial uterine inertia (Table 15). Further, medical
treatment was more successful in relieving cases of partial primary uterine inertia with a
success rate of 59.09 per cent than in cases of primary uterine inertia wherein, the success
rate was 23.33 per cent.
4.15.2 Vaginal manipulative procedure
Vaginal manipulative procedures to relive dystocia were attempted in 80 cases in
which the cause of dystocia was fetal in origin. The treatment was attempted using either
gloved finger or a sponge forceps provided the fetal parts were easily accessible and the
birth canal fairly relaxed. The manipulative procedures were successful in relieving
dystocias in 46.25 per cent of the animals (Table 16). Further, vaginal manipulative
procedures were more successful in correction and delivery of fetuses with flexion of the
limbs (78.12 %) than in animals with fetal head deviation (25.00 %).
80
Table 15. Efficacy of medical treatment for relieving dystocia in bitch (N=104)
Type of Dystocia No of Animals
No of animals responding to medical
treatment
Success Rate (%)
Primary uterine inertia 60 14 23.33
Partial primary uterine inertia 44 26 59.09
Total 104 40 38.46
Table 16. Efficacy of vaginal manipulative procedures for relieving dystocia in
bitches (N=80)
Type of Dystocia No of Animals
No of animals responding to manipulative
procedures
Success Rate (%)
Lateral deviation of the head 48 12 25.00
Unilateral or bilateral limb flexion 32 25 78.12
Total 80 37 46.25
81
4.15.3 Cesarean section
Out of a total of 240 cases of dystocia handled during the course of present
investigation, medical therapy was successful in 40 animals (16.67 %) and vaginal
manipulative procedures in 37 animals (15.41 %). The remaining 163 animals (67.91 %)
had to be subjected for cesarean section either because they failed to respond to medical
therapy or vaginal manipulative procedures (Table 17). Further, cases were also subjected
to cesarean section directly without trying any medical or vaginal manipulative
procedures.
4.16 Pre and post-operative evaluation of patients being subjected for cesarean
section
4.16.1 Rectal temperature
The mean rectal temperature prior to administration of premedicative agents in
animals which were to be anaesthetized by Group I was 101.78 +/- 0.95 F. The rectal
temperature droped marginally to 101.04±0.800 F immediately after induction of
anaesthesia with propofol and the rectal temperature was still lower at the time of
recovery from anaesthesia (100.46±0.45 F). A similar trend was noticed in patients
allotted to other three groups. The rectal temperature prior to premedication, immediately
after induction of anaesthesia and immediately after recovery from anaesthesia were
101.96±0.98, 101.96±0.98 and 100.70±0.810 F respectively, in animals subjected to
cesarean section with Group II. The respective rectal temperature was 101.90±1.11,
101.24±0.83 and 100.43±1.56 F in animals subjected to cesarean section with isoflurane
and was 101.80±1.42 F, 100.14±1.30 and 100.70±1.110 F in animals subject to cesarean
82
Table 17. Indications for cesarean section in bitches (163).
Indication No. of animals Percentage
Failure of medical therapy 64 39.26
Failure of vaginal manipulative procedures 43 26.38
Abnormal birth canal 12 7.37
Other causes (fetal emphysema/poor general body condtion etc..) 44 26.99
Grand total 163 100.00
83
section with epidural analgesia. (Table 18). However, the variations in the rectal
temperature prior to premedication, after induction of anesthesia and post recovery was
not significant (P≤0.05) within a particular group or between groups of animals subjected
to different anesthetic protocols.
4.16.2 Heart rate
Table 19 presents the mean changes in heart rate in bitches prior to administration
of preanaesthetic agent, immediately after induction of anaesthesia and immediately after
recovery from anaesthesia. Prior to premedication the mean heart rate in animals allotted
to propofol, propofol plus ketamine, Isoflurane and epidural anaesthesia were
80.16±1.60, 79.53±7.36, 86.63±5.69 and 76.16±8.75 per minute respectively. The
corresponding heart rate immediately after induction of anesthesia was 50.67±1.00,
55.13±8.02, 55.86±2.18 and 59.37±8.80 per minute. Further, the respective values were
85±8.65, 85.93±9.45, 81.93±1.85 and 70.60±2.25 immidiately after recovery from
anaesthesia. The heart rate did not exhibit any significant (P<0.05) variation either within
a group or between the groups.
4.16.3 Pulse rate
The mean changes in pulse rate (No per minute) in bitches prior to administration
of preanaesthetic agent, immediately after induction of anesthesia and immediately after
recovery from anaesthesia is presented in Table 20. Prior to premedication the mean
pulse rate in animals allotted to propofol, propofol plus ketamine, Isoflurane and epidural
analgesia were 92.06±12.60, 94.53±8.53, 80.46±15.66 and 72.06±18.88 per minute
respectively. The corresponding values immediately after induction of anesthesia were
84
Table 18. Mean (±SE) changes in rectal temperature (OF) of bitches subjected to
cesarean section under different anaesthetic protocols and epidural
analgesia.
Anaesthetic protocol Pre-sedation Pre-surgical Post-recovery
Propofol (N=12) 101.78±0.95 101.04±0.80 100.46±0.45
Propofol-Ketamine(N=12) 101.96±0.98 101.96±0.98 100.70±0.81
Isoflurane(N=12) 101.90±1.11 101.24±0.83 100.43±1.56
Epidural(N=12) 101.80±1.42 100.14±1.30 100.70±1.11
Table 19. Mean (±SE) changes in heart rate (number per minute) of bitches
subjected to cesarean section under different anesthetic protocols and
epidural analgesia.
Anaesthetic protocol Pre-sedation Pre-surgical Post-recovery
Propofol (N=12) 80.16±1.60a 50.67±1.00b 85±8.65 a
Propofol-Ketamine(N=12) 79.53±7.36 a 55.13±8.02 b 85.93±9.45 a
Isoflurane(N=12) 86.63±5.69 a 55.86±2.18 b 81.93±1.85 a
Epidural(N=12) 76.16±8.75 a 59.37±8.80 b 70.60±2.25 a
Note: Means bearing any one common superscript between groups do not differ significantly
(P>0.05)
Table 20. Mean (±SE) changes in pulse rate (number per minute) of bitches
subjected to cesarean section under different anaesthetic protocols and
epidural analgesia
Anaesthetic protocol Pre-sedation Pre-surgical Post-recovery
Propofol (N=12) 92.06±12.60 83.87±11.50 61.47±09.76
Propofol-Ketamine(N=12) 94.53±8.53 75.33±1972 90.93±7.49
Isoflurane(N=12) 80.46±15.66 73.86±22.15 73.93±22.14
Epidural(N=12) 72.06±18.88 73.33±18.90 79.60±22.20
85
83.87±11.50, 75.33±1972, 73.86±22.15and 73.33±18.90 per minute while it was
61.47±09.76, 90.93±7.49, 73.93±22.14and 79.60±22.20 per minute respectively after
recovery from anaesthesia. The pulse rate did not exhibit any significant (P≤0.05)
variation either within a group or between the groups.
4.16.4 Respiratory rate
The mean changes in respiratory rate (No per minute) in bitches prior to
administration of preanaesthetic agent, immediately after induction of anesthesia and
immediately after recovery from anaesthesia under different anaesthetic protocols is
presented in Table 21. Prior to premedication the mean respiratory rate in animals allotted
to propofol, propofol plus ketamine, Isoflurane and epidural analgesia were 17.80±7.27,
16.60±05.14, 15.13±05.51 and 17.73±2.13 per minute respectively. The corresponding
value immediately after induction of anesthesia was 12.80±2.45, 13.40±3.20, 11.06±1.96
and 13.60±1.82 while, it was 15.26±09.93, 13.06±8.88, 17.20±01.58, and 18.60±1.55 per
minute after recovery from anesthesia. The respiratory rate did not exhibit any significant
(P≤0.05) variation either within a group or between the groups.
4.16.5 Hemoglobin concentration
Table 22 presents the mean changes in hemoglobin concentration in bitches prior
to administration of preanaesthetic agent, immediately after induction of anesthesia and
immediately after recovery from anesthesia. Prior to premedication the mean hemoglobin
concentration in animals allotted to propofol, propofol and ketamine, Isoflurane and
epidural analgesia were 11.31±0.92, 13.68±0.54, 13.79±0.62 and 13.26±0.53 gm percent
respectively. The corresponding values immediately after induction of anesthesia were
86
Table 21. Mean (±SE) changes in respiratory rate (number per minute) of bitches
subjected to cesarean section under different anaesthetic protocols and
epidural analgesia
Anaesthetic protocol Pre-sedation Pre-surgical Post-recovery
Propofol (N=12) 17.80±7.27a 12.80±2.45b 15.26±09.93 a
Propofol-Ketamine(N=12) 16.60± 05.14 a 13.40±3.20 b 13.06±8.88 a
Isoflurane(N=12) 15.13±5.51 a 11.06±1.96 b 17.20±1.58 a
Epidural(N=12) 17.73±2.13 a 13.60±1.82 b 18.60±1.55 a
Note: Means bearing any one common superscript between groups do not differ significantly
(P>0.05)
Table 22. Changes in mean ±SE haemoglobin concentration in bitches subjected to
cesarean section under different anaesthetic protocols and epidural
analgesia
Mean Hb (g/dl)
Anaesthetic protocol Pre-sedation Pre-surgical Post-recovery
Propofol (N=12) 11.31±0.92 11.11±0.93 10.32±1.1
Propofol-Ketamine(N=12) 13.68±0.54 13.06±0.56 11.61±1.02
Isoflurane(N=12) 13.79±0.62 13.19±0.51 11.21±1.05
Epidural(N=12) 13.26±0.53 12.25±0.5 11.81±0.41
87
11.11±0.93, 13.06±0.56, 13.19±0.51 and 12.25±0.5g per cent respectively and it was
10.32±1.1, 11.61±1.02, 11.21±1.05 and 11.81±0.41g per cent respectively after recovery
from anesthesia. The hemoglobin concentration did not exhibit any significant (P≤0.05)
variation either within a group or between the groups.
4.16.6 Total leukocyte count
Table 23 presents the mean changes in total leukocyte count in bitches prior to
administration of preanaesthetic agent, immediately after induction of anesthesia and
after recovery from anesthesia. Prior to premedication the total leukocyte count in
animals allotted to propofol, propofol and ketamine, Isoflurane and epidural anesthesia
were 18.99 ± 2.43, 21.05 ± 1.71, 21.93 ± 2.02 and 20.09 ± 1.87 103/cmm respectively.
The corresponding values immediately after induction of anesthesia were 17.41 ± 2.32,
20.72 ± 1.76, 19.97 ± 2.20 and 19.70 ± 1.88 103/cmm and was 17.21 ± 2.22, 20.12 ± 1.1,
18.46 ± 1.52 and 19.11 ± 1.79 103/cmm respectively after recovery from anesthesia. The
total leukocyte count did not exhibit any significant (P≤0.05) variation either within a
group or between the treatments.
4.16.7 Platelet count
Table 24 presents the mean changes in Platelet count in bitches prior to
administration of preanaesthetic agent, immediately after induction of anesthesia and
immediately after recovery from anesthesia/analgesia. Prior to premedication the Platelet
count in animals allotted to propofol, propofol plus ketamine, Isoflurane and epidural
analgesia were 3.24±0.95, 3.32±1.00, 3.34±0.97 and 3.58±1.02 lakh/cmm respectively.
The corresponding values immediately after induction of anesthesia were 3.14±0.97,
88
Table 23. Changes in mean ±SE total leucocyte count in bitches subjected to
cesarean section under different anaesthetic protocols and epidural
analgesia
Total leucocyte count (103/cmm)
Anaesthetic protocol Pre-sedation Pre-surgical Post-recovery
Propofol (N=12) 18.99 ± 2.43 17.41 ± 2.32 17.21 ± 2.22
Propofol-Ketamine(N=12) 21.05 ± 1.71 20.72 ± 1.76 20.12 ± 1.11
Isoflurane(N=12) 21.93 ± 2.02 19.97 ± 2.20 18.46 ± 1.52
Epidural(N=12) 20.09 ± 1.87 19.70 ± 1.88 19.11 ± 1.79
Table 24. Changes in mean ± SE platelet count in bitches subjected to cesarean
section under different anaesthetic protocols and epidural analgesia
Platelet count (Lakhs/Cmm)
Anaesthetic protocol Pre-sedation Pre-surgical Post-recovery
Propofol (N=12) 3.24±0.95 3.14±0.97 3.07±0.89
Propofol-Ketamine(N=12) 3.32±1.00 3.29±0.90 3.14±0.89
Isoflurane(N=12) 3.34±0.97 3.31±0.97 3.11±0.86
Epidural(N=12) 3.58±1.02 3.44±1.03 3.24±0.95
89
3.29±0.90, 3.31±0.97 and 3.44±1.03 lakhs/cmm and was 3.07±0.89, 3.14±0.89,
3.11±0.86 and 3.24±0.95 lakhs/cmm respectively after the recovery from
anesthesia/analgesia. The Platelet count did not exhibit significant (P≤0.05) variation
between stages within a group or between the groups.
4.16.8 Alanine amino transferase (ALT)
The mean changes in ALT concentration in bitches prior to administration of
preanaesthetic agent, immediately after induction of anesthesia and immediately after
recovery from anesthesia/analgesia is presented in Table 25. Prior to premedication the
ALT concentration in animals allotted to propofol, propofol plus ketamine, Isoflurane
anaesthesia and epidural analgesia were 26.90±6.22, 28.91±2.87, 27.00±6.24 and
23.33±4.58 U/L respectively. The corresponding values immediately after induction of
anesthesia were 24.87±5.16, 24.85±3.33, 23.22±2.67 and 21.58±2.8 U/L respectively and
were 22.48±4.56, 21.07±5.36, 23.68±5.88 and 21.07±4.88 U/l respectively after
recovery. The ALT concentration did not exhibit any significant (P≤0.05) variation either
within a group or between the groups.
4.16.9 Blood Urea Nitrogen
The mean changes in blood urea nitrogen (BUN) concentration in bitches prior to
administration of preanaesthetic agent, immediately after induction of anesthesia and
immediately after recovery from anaesthesia are presented in Table 26. In animals
allotted to propofol, propofol plus ketamine, Isoflurane anaesthesia and epidural
analgesia the BUN concentration prior to premedication were 22.41±4.14, 28.54±3.43,
25.58±3.65 and 26.33±3.35mg/dl respectively. The corresponding BUN values
90
Table 25. Changes in mean±SE serum ALT in bitches subjected to cesarean section
under different anaesthetic protocols and epidural analgesia
ALT (U/l)
Anaesthetic protocol Pre-sedation Pre-surgical Post-recovery
Propofol (N=12) 26.90±6.22 24.87±5.16 22.48±4.56
Propofol-Ketamine(N=12) 28.91±2.87 24.85±3.33 21.07±5.36
Isoflurane(N=12) 27.00±6.24 23.22±2.67 23.68±5.88
Epidural(N=12) 23.33±4.58 21.58±2.8 21.07±4.88
Table 26. Changes in mean ± SE serum BUN in bitches subjected to cesarean
section under different anaesthetic protocols and epidural analgesia.
BUN (mg/dl)
Anaesthetic protocol Pre-sedation Pre-surgical Post-recovery
Propofol (N=12) 22.41±4.14 21.79±4.12 21.10±3.92
Propofol-Ketamine(N=12) 28.54±3.43 25.78±3.58 24.81±3.92
Isoflurane(N=12) 25.58±3.65 22.70±3.55 21.40±3.80
Epidural(N=12) 26.33±3.35 25.00±3.8 23.50±2.98
91
immediately after induction of anesthesia were 21.79±4.12, 25.78±3.58, 22.70±3.55 and
25.00±3.8mg/dl respectively. Further, the corresponding BUN levels were and
21.10±3.92, 24.81±3.92, 21.40±3.80 and 23.50±2.98 mg/dl respectively immediate to
recovery from anaesthesia. The BUN concentration did not exhibit significant (P≤0.05)
variation either within a group or between the groups.
4.16.10 Serum Creatinine
The Table 27 presents the mean changes in serum creatinine concentration in
bitches prior to administration of preanaesthetic agent, immediately after induction of
anesthesia and immediately after recovery from anaesthesia/analgesia. Prior to
premedication the serum creatinine concentration in animals allotted to propofol,
propofol and ketamine, Isoflurane and epidural anesthesia were 1.01±0.08, 0.88±0.07,
0.98±0.06 and 0.93±0.06mg/dl respectively. The corresponding values of serum
creatinine concentration immediately after induction of anesthesia were 1.01±0.08,
0.95±0.07, 0.90±0.07 and 0.90±0.07 mg/dl and immediate to recovery from
anaesthesia/analgesia its level was 1.02±0.08, 1.04±0.09, 1.18±0.07 and 0.92±0.08 mg/dl
respectively in the corresponding group of animals. The serum creatinine concentration
did not exhibit significant (P≤0.05) variation either within a group or between the groups.
4.16.11 Serum calcium
The Table 28 presents the mean changes in serum calcium concentration in
bitches prior to administration of preanaesthetic agent, immediately after induction of
anesthesia/analgesia and immediately after recovery from anaesthesia/analgesia. Prior to
premedication the serum calcium concentration in animals allotted to propofol, propofol
92
Table 27. Changes in mean ±SE serum creatinine in bitches subjected to cesarean
section under different anesthetic protocols and epidural analgesia
Serum Creatinine (mg/dl)
Anaesthetic protocol Pre-sedation Pre-surgical Post-recovery
Propofol (N=12) 1.01±0.08 1.01±0.08 1.02±0.08
Propofol-Ketamine(N=12) 0.88±0.07 0.95±0.07 1.04±0.09
Isoflurane(N=12) 0.98±0.06 0.90±0.07 1.18±0.07
Epidural(N=12) 0.93±0.06 0.90±0.07 0.92±0.08
Table 28. Changes in mean ± SE serum calcium in bitches subjected to cesarean
section under different anesthetic protocols and epidural analgesia
Serum calcium (g/dl)
Anaesthetic protocol Pre-sedation Pre-surgical Post-recovery
Propofol (N=12) 9.83±0.13 9.67±0.12 9.76±0.14
Propofol-Ketamine(N=12) 9.48±0.39 9.50±0.28 9.82±0.15
Isoflurane(N=12) 9.20±0.3 9.49±0.21 9.7±0.16
Epidural(N=12) 9.4±0.37 9.44±0.36 9.67±0.28
93
and ketamine, isoflurane anesthesia and epidural analgesia were 9.83±0.13, 9.48±0.39,
9.20±0.3 and 9.4±0.37 mg/dl respectively. The corresponding values of serum calcium
immediately after induction of anesthesia were 9.67±0.12, 9.50±0.28, 9.49±0.21 and
9.44±0.36 mg/dl respectively the serum calcium levels was 9.76±0.14, 9.82±0.15,
9.7±0.16 and 9.67±0.28 mg/dl in respective group after recovery. The serum calcium
concentration did not exhibit significant (P<0.05) variation either within a group or
between the groups.
4.16.12 Random Blood Glucose
The mean changes in Random Blood Glucose (RBG) concentration in bitches
prior to administration of preanaesthetic agent, immediately after induction of anesthesia
and immediately after recovery from anesthesia/analgesia is presented in Table 29. Prior
to premedication the RBG concentration in animals allotted to propofol, propofol plus
ketamine, Isoflurane and epidural anesthesia were180.29±21.53, 170.59±21.65,
168.05±22.56 and 162.45±5.08mg per cent respectively. The corresponding values of
blood glucose immediately after induction of anesthesia were 179.65±6.89, 168.80±7.16,
159.07±6.33 and 161.73±5.39mg per cent and was 180.15±5.45, 169.49±5.31,
162.49±5.13 and 158.03±5.5mg per cent respectively after recovery from anesthesia. The
RBG concentration did not exhibit significant (P<0.05) variation either within a group or
between the groups.
4.17 Electrocardiographic studies
The electrocardiography was carried out in every patient subjected to cesarean
section once prior to the injection of sedative and again after complete surgical recovery.
94
Table 29. Changes in mean ± SE random blood glucose in bitches subjected to
cesarean section with different anesthetic protocols and epidural
analgesia
Random Blood Glucose (mg/dl)
Anaesthetic protocol (N=12) Pre-sedation Pre-surgical Post-
recovery
Propofol 180.29±21.53 179.65±6.89 180.15±5.45
Propofol-Ketamine 170.59±21.65 168.80±7.16 169.49±5.31
Isoflurane 168.05±22.56 159.07±6.33 162.49±5.13
Epidural 162.45±5.08 161.73±5.39 158.03±5.5
95
There were no major changes in electrocardiography in all the animals subjected to
cesarean section with the different anesthetic protocols.
4.18 Evaluation of different anesthetic protocols followed for cesarean section in
bitches
The important evaluation indicators like ease of induction, time taken for recovery
from anaesthesia and degree of cardiac and respiratory depression in the neonates
recorded for different anaesthetic protocols followed are presented in Table 30. Animals
could be easily induced into the third plane of anesthesia with propofol as well as
propofol plus ketamine anesthesia. However, with Isoflurane, considerable struggling
was observed in most of the animals during the initial stage of induction of anaesthesia.
With epidural analgesia, on other hand, considerable degree of struggling was observed
and in some animals the degree of analgesia was only partial.
The skeletal muscle relaxation was excellent when anesthesia was induced with
Isoflurane and it was good with both propofol and propofol plus ketamine general
anesthesia. While, it was poor with epidural analgesia (Animals who took a very long
time to recover). The time taken for recovery from anesthesia after the completion of
surgical procedure are presented in Table 30 and the recovery was almost immediate in
animals anaesthetized with Isoflurane. It was slightly longer (4.18+/-0.6 minutes) with
propofol anesthesia followed by Propofol plus ketamine anesthesia (10.14+/-0.2
minutes). The time taken for recovery was longest (62.17+/-5.85 minutes) in animals
where epidural analgesic technique was used to conduct cesarean section. However,
puppies delivered using epidural technique of analgesia had very little cardiovascular and
96
Table 30. Evaluation of different anesthetic protocols, epidural analgesia for
cesarean section in bitches
Evaluation Parameter
Anesthetic protocols
Propofol Propofol-Ketamine Isoflurane Epidural
Ease of induction of anaesthesia Easily induced Easily induced
Slight struggling at the time of
induction Struggling
Skeletal muscle relaxation Good Good Profound Poor
Time taken for recovery from anesthesia after surgery (minutes)
2-7
(4.18±0.6) 5-15
(10.14±0.2) Almost
immediate 45-130
(62.17±5.85)
Degree of cardio vascular and respiratory depression in the neonates
Some degree Some degree Some degree Little effect
97
respiratory depression and were found squealing immediately after delivery. Whereas, in
puppies born following cesarean section with other anesthetic protocols varying degrees
of cardiovascular and respiratory depression was observed and generally the time taken
for lifting the head varied from 5-7 minutes.
4.21 Puppy survivable rate in bitches subjected to caesarean section using different
anesthetic protocols
The puppy survival rate born to bitches subjected to cesarean section using
different anaesthetic protocols is presented in Table 31. A total of 279 fetuses were
delivered from 48 animals following surgery and 262 (93.9%) of them were delivered
alive. The per centage of live puppies per bitch delivered was highest in animals where
cesarean section was carried out under epidural analgesia (97.05%). The puppy survival
rate in groups of animals wherein cesarean section was carried out employing propofol,
Propofol plus ketamin and Isoflurane were 92.18, 92.95 and 93.42 per cent respectively.
98
Table 31. Puppy survivable rate of bitches subjected to caesarean section under
different anaesthetic protocols and epidural analgesia.
Anaesthetic protocol used
No of animals
Total no of fetuses delivered
No of Live fetuses
Per centage of live fetuses delivered
Propofol 12 64 59 92.18
Propofol-Ketamine 12 71 66 92.95
Isoflurane 12 76 71 93.42
Epidural 12 68 66 97.05
Total 48 279 262 93.90
Discussion
V DISCUSSION
5.1 Duration of Gestation
Compared with larger animals, the bitch is considered to be a difficult obstetrical
patient in several respects. Primarily, there is an apparent wide variation in the duration
of pregnancy when the dates of mating alone are used for calculation of the gestational
age. The canine breeder usually calculates the gestation period as the interval from the
day of first mating to the day of parturition and believes that the parturition should be
initiated between 62 to 64 days. However, in practice the gestation length in dog when
expressed as the interval from an initial or a single mating to parturition is reported to
range from 58 to 71 days (Anderson 1970; Holst and Phemister 1971; Anderson and
Simpson 1973; Holst and Phemister 1974; Concannon et al.,1975; Sokolowski 1980).
Similar observations were also made in the present study, the duration of pregnancy in
240 bitches with dystocia ranged between 57 to 71 days with an average of 62.16±3.95
days. It was also observed in the present study that only one third of the animals
(33.34%) presented with the complaint of dystocia had completed a gestation period of
63-65 days.
Some studies have attempted to determine the factors affecting the variability in
the gestational length. The influence of the breed on the length of gestation has been
controversial. Okkens et al., (1993) reported that breed influenced the duration of
gestation in bitches. The most recent study by Okkens et al., (2001) had at least 12
bitches representing each breed. They reported that West Highland white terrier had
longer gestation duration than German shepherd, Labrador Retrievers and Doberman.
100
The same authors analyzing atleast 5 bitches from each breed had previously reported
that German shepherd dogs had shorter gestation duration when compared to Boxer,
Burmese Mountain dogs, Old English sheep dog and Bouvier-Desflanders (Okkens et al.,
1993). Eilts et al., (2005) reported that compared to Labrador Retrievers, the German
shepherds, Golden Retrievers and Hounds were more likely to have longer gestation
length. However, other investigators have found no breed effect on gestation length
(Kutzler et al., 2003).
Litter size is another factor which has been studied for its influence on the length of
gestation in bitches. Litter of a single Beagle pup had longer gestation duration in one
study (Holst and Phemister, 1974) and litter size was negatively correlated with gestation
length in other studies (Okkens et al., 1993; Okkens et al., 2001). However, in two other
reports (Kutzler et al., 2003) the litter size did not affect the duration of
gestation.
The effect of age or parity on gestation length has not been studied extensively in
bitches. A single study found primiparus bitches to have similar gestation duration as
multiparus bitch (Okkens et al., 1993). Within breed, age had no effect on litter size
(Okkens et al., 2001). Eilts et al., (2005) reported that age or parity had no effect on
gestation length.
It was not the objective of the present study to investigate the factors influencing
the length of gestation in dogs. Furthermore, the number of animals in each breed was
considered too small to draw any conclusions on the influence of breed, litter size, age or
parity on the length of gestation in dogs. Nevertheless, if factors such as breed, age,
101
parity or litter size have any effect on the length of gestation in dogs, it is unlikely that it
contributes significantly to the high variability (58 to 72 days)observed in the interval
from mating to whelping between individual dogs when the matings are unplanned.
A more likely explanation for the apparent variability in the gestation length of
bitches appears to be due to the tendency of the female to accept the male from 5 to 6
days before to 2 to 3 days after ovulation. Additional variability may be caused by the
prolonged survival of ova (up to 3 days; Holst and Phemister, 1971) and of spermatozoa
(up to 6 days; Doak et al., 1967; Concannon et al., 1983).
In human obstetrics, ultrasonography has been widely used to determine the
gestational age and to assess the fetal wellbeing. Transabdominal ultrasonographic
examination also has a wide scope for its application in small animal obstetrics.
Ultrasonography has been particularly useful in early pregnancy diagnosis (England et
al., 1990; Yeager and Concannon, 1990; Yeager et al., 1992; England and Yeager, 1993).
It has also been used for estimation of gestational age and prediction of litter size and
date of parturition (Concannon, 2000; Kutzler et al., 2003). More recently, the Veterinary
Obstetrician is looking forward to the use of ultrasonography for assessment of the
fertility and wellbeing of fetuses and duration of pregnancy as he is aware that gestational
age calculated on the basis of mating history are unreliable.
Ultrasonographic equipments specifically designed for use in small animal
practice are now available for Veterinary Obstetrician. These equipments have been
precalibrated and provide gestational age from the measurements of biparietal fetal head
diameter or crown rump length and the gestational age is displayed in days from the day
102
of preovulatory LH surge. It is known that the gestational period calculated from the day
of LH surge to the onset of parturition is fairly constant in bitches and in the reports of
Concannon et al., (1983), the interval from the day of peak concentration of serum LH to
parturition was less variable and ranged from 64 to 66 days and averaged 65.1 ± 0.1 days.
In the present study, the gestational age in 240 bitches presented with the
complaint of dystocia was determined using a trans-abdominal ultrasonography designed
specifically for Veterinary use. The gestational age was obtained by the measurements of
biperital fetal head diameter. It was observed that the gestational age as determined by
ultrasonography also varied widely from 59 to 68 days and in only 27 per cent of the
animals the gestational age was determined as 63-65 days at the time of parturition.
Although, much has been learnt regarding the application of B-mode
ultrasonography in small animal reproduction, concerns have been raised regarding its
utility for accurate estimation of fetal age and prediction of parturition date in view of
great differences in their size, confirmation and litter size. Bhagirathi, (2008) attempted
to establish to predict the parturition date in bitches. Her study could not clearly establish
that ultrasonography is accurate for determining the gestational age in bitches in spite of
categorizing the animals with respect to their body weight. It was concluded that it may
be inaccurate to predict the date of parturition on the basis of Ultrasonographic
measurements using a single universal formulae although correction factors may have
been suggested. It was recommended that, parturition date may be predicted more
accurately when the prediction tables are developed for each class or breed. In the present
study, 240 bitches with dystocia belong to eighteen different breeds and the gestational
103
age as determined by Ultrasonographic measurement varied widely between the breeds
concurring with the statement of Bhagirathi (2008), that ultrasonography is not very
accurate for estimation of gestational age in bitches unless the criteria are developed for
each class or breed of the animal.
5.2 Signs of impending parturition
In the present study, the behavioral signs observed by the owner at the time of
onset of parturition were recorded and is presented in Table 5.The most common signs
reported by the owner were nesting (30.83%) and restlessness (29.16%). Excessive
panting was reported by the owner in 20 per cent of the dystocia cases. Vomiting and
anorexia were reported infrequently.
The behavioral signs exhibited by a pregnant animal during advance pregnancy
are commonly used by a breeder to determine the approximate gestational age and to
predict the parturition date. However, the observations made in the present study as well
as in the reports of Bennur, (1999) and Bhagirathi, (2008) suggest that the signs are too
variable and inconsistent to be used for determination of gestational age and parturition
date. Further, animals with dystocia also did not exhibit a particular sign which can be
used by the owner with confidence to suggest that the delivery is not progressing
normally. For instance, anorexia which is abnormal was observed in only 10 per cent of
the animals. Similarly, restlessness and panting were not present in over 70% of the
animals. Therefore, more than the behavioral signs, the actual duration of each stage of
parturition or the nature of vaginal discharges may have more relevance for the owner in
identifying a parturition process as normal or abnormal.
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5.3 Nature of vaginal discharges in bitches with dystocia
Table 8 presents the nature of vaginal discharge (colour and odour) exhibited by
animals with history of dystocia. Nearly 50 per cent of animals with dystocia were
presented with history of copious mucoid discharge which was slightly greenish tinged
and was confirmed on further clinical examination. This kind of discharge probably
indicates that either the animal is still in the course of parturition or that the dystocia has
been existing for a very short period of time. It may also indicate that the fetuses are
probably alive. The greenish color of the discharge has been stated to be due to placental
separation (Roberts, 1986) and probably a mild green color may indicate a mild
separation of the placenta enhancing the chances of encountering a live fetus. In the
present study, in most animals exhibiting this kind of discharge, the fetuses were found to
be alive as identified by ultrasonic examination and in those animals which were
subjected for cesarean section, the fetuses delivered were invariably alive.
In 15.42 per cent of the animals, vaginal discharges were very blackish green and
thick indicating a complete placental separation of atleast one fetus in the caudal part of
the uterus. This kind of discharge may indicate the possibility of dystocia being exisisting
for some time and also the possibility of encountering one or more dead fetus. This
statement was collaborated in the present study through ultrasonographic studies which
invariably identified one or more dead fetuses in animals with a thick green or blackish
greenish discharge.
The vaginal discharges were brownish and foul smelling in 33.33 per cent of
cases indicating that dystocia has been exisisting for considerable period of time and the
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possibility of most of the fetuses being invariably dead. In the present study again the
ultrasonographic studies in 80 animals with foul smelling discharge invariably reveled
dead fetuses. In many cases gas in and around the fetuses was identified on ultrasonic
examination.
Hemorrhagic discharges were observed in six (2.5%) animals. One of the animals
with a hemorrhagic discharge turned out to be a case of uterine torsion on cesarean
section and in other five animals, severe vaginal edema was observed suggesting the
possibility of vaginal manipulation and subsequent trauma to the vagina prior to its
presentation to the obstetrical unit. The nature of the vaginal discharge in a bitch with
dystocia may provide a clue regarding the condition of the genital tract and may help in
deciding the choice of treatment for revealing dystocia.
In the present studies, a retrospective analysis of number of dystocia cases
presented between January 1999 and December 2007 revealed that a total of 999 cases
were referred for treatment to the small animal obstetrical section of Veterinary College,
Bangalore. Further, during the year 2008 and 2009 alone, as many as 240 new cases were
brought for treatment. In contrast, in the same obstetrical section, only 84 cases of canine
dystocias were treated between January 1989 and December 1998 (Bennur, 1999). The
steady increase in the number of canine dystocia cases presented for treatment may
possibly be due to an increase in the canine population in the cities and the awareness of
the canine owners and breeders of the availability of specialized obstetrical services.
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5.4 Influence of breed of the bitch on the incidence of dystocia
In the present studies, 18 different breeds were presented with the complaint of
dystocia (Table 01). Nearly 30 per cent of the patients presented were either laborador
retrievers (18.12%) or German Shepards (12.00%). Dystocia in brachycephaplic breeds
like pugs (9.06 %), boxers (9.40) and bull dogs (5.17 %) were also encountered in a
relatively high frequency. Of all dystocia cases presented 8.4 per cent were in
Daschhounds. The incidence of dystocia was least in Basset hounds and in other breeds.
Several studies have documented a significant effect of the breed of the dam on
the incidence of dystocia in canines. The breeds which have been reported to be
particularly predisposed for dystocia include Bosten Terrier (Roberts, 1986), Scottish
terrier (Gaudet, 1985 and Roberts, 1986), Chihuahua (Gaudet, 1985), Daschhound
(Freak, 1948; Gaudet, 1985 and Arthur et al.,1989), Abarden Terrier (Arthur., 1989),
Brachycephalic breeds (Bennet, 1974 and Roberts, 1986), Bosten Terrier (Smith, 1974),
Yorkshire Terrier (Gaudet, 1985), Poodles (Freak, 1962 and Gaudet, 1985), Pomeranian
(Gaudet, 1985), Greyhounds (Sweeney, 1972) Whelsh Coorgi (Freak, 1948; Wright,
1950 and Arthur et al.,1989) and Cocker spaniel (Freak, 1948).
It is interesting to note that in the present study, the highest incidence of dystocia
was encountered in German Shepards and Laborador Retriever; the breeds which have
not been reported to be particularly susceptible for dystocia. German Shepards and
Laboradors also happens to be favourite breeds among canine owners in Bangalore city
and therefore a higher frequency of dystocia recorded in these breeds in the present study
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may be due to a high population of these breeds in the area, rather than due to breed
predisposition.
Of all dystocia cases encountered in the present study 23.63 per cent were in
brachycephalic breeds (Pug, Bull dog and Boxers). Brachycephalic breeds like Pugs and
Bull dogs are being increasingly reared by dog owners and most canine breeders seem to
be aware of a higher risk of dystocia in brachycephalic breeds. There is a wide consensus
among obstetricians that boxers and other brachycephalic breeds are predisposed for
dystocia (Smith, 1965; Bennett, 1974; Roberts, 1986 and Arthur et al 1989). Factors
suggested to be responsible for predisposition of brachycephalic breeds to dystocia
include a slack abdominal musculature making it impossible to lift the fetus upto pelvic
cavity (Bennet, 1974), a chord like structure crossing the lumen of the vagina ventrally
just caudal to cervix (Smith, 1965) and peculiar shape of the fetal head making it difficult
to enter the pelvic inlet (Roberts, 1986 and Arthur et al. 1989).
A higher frequency of dystocia was also encountered in Daschunds (8.40%), a
breed which has also been recognized to be predisposed for dystocia (Freak, 1948;
Gaudet, 1985 and Arthur et al., 1989). Freak (1948), reported that Daschunds may show
anatomically abnormal pelvis and are particularly prone for a particular type of primary
uterine inertia. This observation appears to be substantiated by the results of the present
study wherein nearly 75 per cent of dystocia cases in Daschunds were due to primary
uterine inertia.
Although, mongrels constitute a significant number of canine populations in this
country, dystocias were recorded in only 4.20 per cent. There have been reports in the
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past about the low incidence of dystocia amongst mongrels (Roberts, 1986 and Darveild
and Fors Berg, 1994).
5.5 Influence of Size of the breed on the incidence of dystocia
In the present study, the size of the breed was found to have a significant effect on
the incidence of dystocia in bitches, the incidence being significantly higher in medium
and large sized breeds. Together, they accounted for nearly 77 per cent of dystocia cases
presented for treatment (Table 2). Apparently, this observation may suggest that medium
and large sized breeds are more prone for dystocia. The medium and large breeds were
represented by 12 different breeds and these breeds also happen to be the preferred breeds
among animal lovers and breeders in the city of Bangalore and therefore the apparent
higher incidence of dystocia in medium and large breeds may be more because of their
higher population. On the other hand, Christiansen (1984) claimed that dystocia mainly
occurred in miniature breed because their pups are relatively bigger as compared to the
case in medium and large sized breeds. Studies of Darvelid and Forsberg (1994)
however, could not clearly establish a relationship between the body weight of the bitch
and the incidence of dystocia.
5.6 Influence of age of the bitch on the incidence of dystocia
The frequency of dystocia in the present study was found to be highest in bitches
aged 2-4 years and it gradually declined with the advancing age (Table 3). Bitches less
than four years accounted for nearly 62 per cent of the dystocia cases. The observations
made in the present study are similar to those of Gaudet (1985) and Darvelid and
Forsberg, (1994) who also recorded the highest incidence of dystocia in bitches aged 2-4
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years and 2-3.5 years respectively. Nevertheless, the results of the present study are in
contradiction with those of Freak (1962), Smith (1974) and Freak (1975) who reported
that the animals aged 5 years and above to be more prone for dystocias particularly due to
uterine inertia. The low occurrence of dystocia in animals aged 6 years and above,
observed in the present study may probably be due to the fact that the most canine owners
prefer not to breed aged animals.
5.7 Influence of Parity of the bitch on the incidence of dystocia
In the present study 31.07 per cent of the cases referred were primiparous and the
rest had delivered 1-8 times. The incidence of dystocia decreased progressively with
increase in parity and the least incidence was recorded in animals with more than 5
deliveries (Table 4). The results of the present study are in close conformity with those of
Gaudet (1985) who reported the incidence of dystocia in primipara as 37.00 per cent and
Darveild and Forsberg (1994) who reported that 28 per cent of bitches experiencing
dystocia had not littered before.
5.8 Duration of dystocia
Darveild and Forsberg (1994) reported that the frequency of dead pups was 5 to 8
per cent in bitches that were in second stage of labour for more than 1-41/2 hours before
arrival at the hospital whereas, in those that had been in labour for 5-24hrs the frequency
of dead puppies were more than twice (13.7%). For this reason, several workers
recommend artificial interference if parturition do not progress or the bitch shows weak
irregular contractions upto 2 hours either prior to birth of the first pup or more than 2 hrs
after the delivery of previous pup (Bennet, 1980, Roberts, 1986). On the other hand, if the
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bitch has strong and frequent contractions, Darveild and Forsberg (1994) recommend
Veterinary interference within 20 to 30 minutes.
In the present study however, all the animals presented were in second stage of
labor for atleast 2 hours irrespective of the type of uterine contractions and only 12.50 per
cent animals were presented within in 4 hours after the onset of labor (Table 8), and more
than half the number of cases presented were in labor for atleast 8 hours. These results
are in sharp contrast to those of Darveild and Forsberg (1994) who reported that 22.6 per
cent of cases of dystocia in their study were presented within 1 to 2 hours after the onset
of second stage of labour and only 13 per cent of cases were presented with the history of
dystocia of atleast 6 hours duration. The high percentage of delayed presentations
recorded in the present study could possibly be either due to delayed referral on the part
of the referring Veterinarian or simply due to negligence by the owner.
5.9 Influence of dystocia on temperature, heart, pulse and respiratory rate
The rectal temperature in 240 animals with dystocia averaged 101.840 F and
ranged between 97.60 F and 1040 F (Table 7). In most cases (89%), the rectal temperature
at the time of presentation was within the normal limits (99.50 F to 102.50 F). One animal
had subnormal temperature (97.60 F) and was in extremely toxemic stage at the time of
presentation and the cause of dystocia was later determined to be due to uterine torsion.
An interesting observation made in the present study was that in many animals the rectal
temperature remained within the normal limits inspite of prolonged duration of dystocia
and in the presence of foul smelling vaginal discharges. Nevertheless, higher rectal
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temperature was invariably associated with history of vaginal manipulations by the
referring Veterinarian.
The mean heart, pulse and respiratory rates in 240 animals with dystocia were
within the normal limits. There is no literature available with regard to changes in pulse
and respiratory rate of bitches with dystocia. However, it seems reasonable to assume that
the respiration and pulse rate in dystocia patients may be influenced by a variety of
extraneous factors such as anxiety, transport, hospital environment, degree of handling
etc and therefore, any abnormal changes in the respiratory and pulse rate in animals with
dystocia must take the extraneous factors into consideration. However, it is equally
important to consider the state of the patient as conditions such as toxemia, septicemia or
dehydration may also affect the respiratory and pulse rates.
5.10 Incidence of maternal dystocia in bitches
In the present study dystocia due to maternal causes were encountered in 63.34
per cent of cases treated (Table 10). A high frequency of maternal dystocia as compared
to fetal causes has also been reported by Gaudet, (1985) and Darveild and Forsberg
(1994).
Primary uterine inertia accounted for 63.15 per cent of maternal causes of
dystocia (Table 10). Primary complete uterine inertia has also been reported to be the
most common maternal cause of dystocia in bitches by Jackson, (1972), Bennet, (1974)
and Darveild and Forsberg, (1994). This condition is considered to have a hereditary
disposition in Scottish Terrier (Freak, 1962). Bennet (1974) states that primary complete
uterine inertia is most frequent in bitches of five years and above which could not be
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corroborated by the findings of the present study wherein, primary complete uterine
inertia was most common in animals aged 2-4 years as compared to older animals
(Table 10).
A low litter size has also been reported to be associated with primary complete
uterine inertia (Freak, 1962; Bennet, 1974; Darveild and Forsberg, 1994). In the present
study the litter size in animals with primary complete uterine inertia ranged between 2
and 9 with only 6 animals having litter size of three or fewer pups (14.3%). Primary
complete uterine inertia was also encountered in two other animals with high litter size to
be due to excessive uterine distension.
In the present study, both primary complete and primary partial uterine inertias
were encountered much more frequently in medium and large sized breeds than in small
sized breeds. It has been claimed that dystocias mainly occur in miniature breeds,
because the pups are relatively large (Christianen, 1984). This was, however, not true in
the present study where medium and large sized breeds were somewhat over represented.
A similar observation was also made by Darveild and Forsberg (1994). Other reported
causes of primary complete uterine inertia include hydrallantois, toxic degeneration of
uterus, senility, obesity, lack of exercise and physic disturbances (Freak, 1975; Buckner,
1979 and Arthur et al., 1989).
Primary uterine inertia was the second most frequent cause of maternal dystocia,
the condition being encountered in 28.95 per cent cases. Darveild and Forsberg (1994)
reported the frequency of primary partial uterine inertia in their studies as 30.7 per cent
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and Gaudet (1985) encountered 33 cases of dystocia due to partial primary uterine inertia
in 95 dams.
The rare causes of maternal dystocia encountered in the present study were pelvic
bone abnormalities in six animals, uterine torsion in six animals and vaginal septum in
four other animals. Vaginal septum as a cause of dystocia has been reported by Freak
(1962), Herr, (1978) and Darveild and Forsberg (1994). Uterine torsion has also been
reported to be rare in canines (Brown, 1974; Bennett, 1980; Jones and Joshua, 1988;
Arthur, 1989).
5.11 Incidence of various causes of fetal dystocias in bitches
In the present study, fetal causes of dystocia were encountered in a significantly
lower number of animals (36.66%) as compared to maternal dystocia. Deviations of the
head encountered in more than 50 per cent of fetal dystocia (Table 14). Further, fore limb
flexions as a cause of dystocia were encountered more frequently than the flexion of hind
limbs. In other studies the incidence of fetal mal presentation, position and posture are
reported as 5.4 per cent by Freak, (1962), 13.5 per cent by Gaudet, (1985) and 24.7 per
cent by Darveild and Forsberg (1994).
5.12 Treatment of dystocia
5.12.1 Medical treatment
The treatment of canine dystocia should be based on the cause of dystocia and
involve the use of ecbolics (oxytocin), vaginal manipulative procedures and cesarean
section. Medical treatment using oxytocin, calcium and dextrose are primarily intended to
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reinforce uterine contractions and therefore, can be employed only in cases of primary
complete or primary partial uterine inertia.
In the present study administration of oxytocin alone and oxytocin along with
dextrose and calcium successfully relieved dystocia in 16.66 per cent of cases of primary
complete uterine inertia. The results obtained in the present study are higher than 6.9 per
cent success rates obtained by Gaudet (1985) using oxytocin alone. Perhaps, a slightly
higher success rate obtained in the present study may be due to the inclusion of dextrose
and calcium as a part of medical management of primary uterine inertia. It is possible that
some cases of uterine inertia are caused by subclinical hypocalcaemia and hypoglycemia.
Several authors have documented the beneficial effect of calcium and dextrose in bitch
with dystocia due to uterine inertia (Smith, 1965; Bennett, 1974; Donovan, 1980).
Hypoglycemia has also been documented to cause uterine inertia during parturition
(Buckner, 1979). The successful correction of uterine inertia due to hypoglycemia by
intravenous glucose administration solution has been reported by Bennett, (1974),
Griener (1974) and Jones and Joshua, (1988). Nevertheless, nearly 83 per cent of cases of
primary uterine inertia failed to respond to medical treatment and had to be subjected for
cesarean section.
Primary complete uterine inertia has been recognized as one of the principal cause
of maternal dystocia in bitch (Bennet, 1974). The cause of primary complete uterine
inertia appears to be multiple and include an inherent weakness in the uterine muscle,
overstretching of myometrium by an excessively large fetus, hydrallantois, unusually
large number of fetuses, toxic degeneration due to bacterial infection, fatty infiltration of
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myometrium and senility (Arthur et al., 1989). Freak (1962) stated that low fecundity,
hereditary predisposition and nervous voluntarily inhibition as important causes of
primary complete uterine inertia. Obesity and lack of exercise have also been suggested
to be one of the causes of primary complete uterine inertia (Buckner, 1979).
It is evident from the aforesaid discussion that the causes of primary complete
uterine inertia are complex and in a clinical set up, it is extremely difficult to pin point
any one single cause as responsible for primary uterine inertia. The medical treatment
aimed at augmenting uterine contractions is unlikely to be successful if there is a
hereditary weakness of musculature. Similarly, a over distended uterine musculature also
may not respond to medical therapy. A bitch which is anxious and nervous may become
more nervous in a clinical set up and again may not respond to oxytocin therapy.
Therefore, a poor response in cases of primary uterine inertia to medical therapy as
observed in the present study is on the expected lines. Further, when obstetrician decides
to try medical therapy in cases of primary uterine inertia, he should keep in mind that a
high per centage of animals may fail to respond and may have to be subjected for
cesarean section. In trying medical therapy, an obstetrician may be losing valuable time
in terms of life of the puppy as oxytocin injections may induce enough contractions of the
uterus to cause separation of the placenta but not the expulsion of fetus. Further, oxytocin
may also cause constriction of umbilical cord leading to fetal anoxia and subsequent fetal
acidosis. It is therefore seems reasonable to suggest that cesarean section should be the
first line of treatment for all cases of primary complete uterine inertia to maximize fetal
survival rate.
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The success rate using medical therapy was much more encouraging in cases of
primary partial uterine inertia, with nearly a third of all cases responding to medical
therapy. Typically, in these cases, the bitch had delivered one or more fetuses and
subsequently the uterine contractions had ceased to resume. A higher success rate with
the use of calcium and dextrose along with oxytocin may suggest that cases of primary
partial uterine inertia may be more due to exhaustion of uterine musculature rather than
its primary weakness. Therefore, supplementation of energy source may be particularly
helpful to augment uterine contractions and help to correct uterine inertia. In view of a
better efficacy of medical therapy in cases of partial uterine inertia, it should be tried as
the first line of treatment rather than subjecting them straight away to cesarean section.
5.12.2 Vaginal manipulative procedures
In the present study, fetal dystocia were encountered in a relatively low frequency
(36.66%) and vaginal manipulative procedures using gloved fingers or sponge forceps
was successful in relieving 62.5 per cent of cases of obstructive dystocia and the rest had
to be subjected to cesarean section. This was in sharp contrast to the success rate with
medical therapy in cases of maternal dystocia wherein nearly 70 per cent of cases have to
be subjected for cesarean section to relieve dystocia.
Vaginal manipulative procedures are not frequently employed by the Veterinary
Obstetrician to relieve dystocia in bitches. In many cases, the procedure may have to be
carried out in the presence of the owner which could be very distressing to him. Also,
vaginal sponge forceps are not commonly available to the practicing Veterinarian.
Further, in many cases, the fetus may be alive and the Obstetrician may be apprehensive
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of using forceps to correct any abnormal alignments. Nevertheless, vaginal manipulative
procedures are extremely useful to relieve obstructive dystocia particularly when the
fetus is dead.
5.12.3 Cesarean section
In the present study, dystocia could be relived only by cesarean section in 163 out
of 240 cases (63.75%) encountered during the course of this investigation (Table 17). In a
retrospective study of 116 cases, Gaudet (1985) reported that nearly 60 per cent of cases
required cesarean section. In a similar retrospective study of 182 cases of canine dystocia,
Darveild and Forsberg (1994) reported that 65.7 per cent of bitches with dystocia
required cesarean section. These reports as well as the results of the present investigation
clearly indicate that cesarean section is the most commonest form of treatment to relieve
dystocia in canines. The frequency of conducting cesarean section to relieve dystocia in
canines far higher than in large ruminants. It is possible that the small size of the animal,
multiparous nature, a long duration of delivery and the demands by the owner to deliver
as many live puppies as possible due to commercial considerations may force the
obstetrician to increasingly employ cesarean section in bitch.
The surgical technique of cesarean section has been fairly well standardized;
therefore, the focus is on maximizing fetal survival rate in patients subjected to cesarean
section and this has centered around the development of an anesthetic protocol which has
minimum respiratory and cardiovascular depressive effects on the dam and the
neonate(s). The selection of the anesthetic protocol, is vital to maximise this objective
and therefore, evaluation of different anesthetic protocols becomes important.
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In the present study, four different anesthetic protocols were evaluated for
cesarean section in bitches. Two of the protocols used involved induction and
maintenance of anesthesia by intravenous infusion of the anesthetic solution. The
anesthetic protocol by intravenous infusion evaluated were Propofol alone or a
combination of Propofol and ketamine. These two anesthetic protocols were evaluated as
the Veterinarians are most familiar with intravenous administration of anesthesia for
abdominal surgery in canines. Propofol and ketamine are also commonly available even
in small places and at present are being extensively used by Veterinarians for abdominal
surgeries.
The third protocol evaluated for cesarean section involved the induction and
maintenance of general anesthesia using an inhalant anesthetic agent namely Isoflurane.
This technique requires the use of the Boyle’s anesthetic apparatus and at present is
available only in specialized Veterinary hospitals or clinics. Cesarean sections in
specialized Veterinary clinics/hospitals are generally being carried out employing
inhalant anesthetic agents.
The fourth protocol evaluated in the present study involved epidural
administration of Lignocane hydrochloride. This technique is the cheapest of all the
protocols and has the least side effects.
One of the main objectives of the present study was to evaluate different
anesthetic protocols with regard to their safety on the mother and the puppies. Therefore,
it became necessary that the anesthetic protocol was evaluated only in mothers with
dystocia carrying live puppies. So, in the present study, an ultrasound examination was
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carried out on all patients who were being subjected to cesarean section and only those
patients with evidence of live fetuses were included for evaluating the effect of anesthetic
protocol. The viability of the fetus was determined on the basis of the fetal heart rate and
fetal moments.
5.12.3.1 Effect of premedication and anesthetic protocol on clinical, hematological
and blood biochemical parameters
Irrespective of the type of anesthetic protocol used, all animals were premedicated
with Diazepam. The primary objective of premedication was to reduce the anxiety,
decrease the pain, reduce the dose of anesthesia and facilitate muscle relaxation and help
the clinician in pre-surgical preparation including clipping and shaving of the surgical site
and swabbing (Dennis and Joanna, 2002). Several other pre-anesthetic agents have been
employed for cesarean section in dogs and include phenothiazines (acepromazine), and
alpha2 agonists like xylazine, medetomidine, detomidine and romifidine (Dennis and
Joanna, 2002). In the present study, however, only diazepam was employed as
phenothiazines and alpha2 agonists have been reported to have depressive effects on the
fetal respiratory and cardiovascular system. However, Moon et al., (1998) has opined that
the type of drug used for pre medication did not appear to affect the fetal outcome,
provided appropriate doses and effects on dam’s condition are considered.
In addition to diazepam, all animals were also administered atropine sulphate an
anticholinergic agent prior to induction of anesthesia. Anticholinergic agents are known
to prevent bradycardia, excessive salivation and to reduce upper airway secretions
(Dennis and Joanna, 2002).
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The rectal temperature was taken in all the animals prior to administration of
diazepam and atropine sulphate and the temperature was found to be within the normal
range (Table 18). The normal rectal temperature recorded in all the animals prior to
sedation possibly suggest the absence of an ongoing septicemia process which is
expected as the ultrasound scan revealed live fetuses.
The rectal temperature was again taken just prior to surgical incision which was
an average about 10 minutes after sedation and the temperature in all the animals
irrespective of the type of anesthesia used remained within the normal limits (Table 18)
suggesting that diazepam and type of anesthesia used had little effect on the rectal
temperature. Similarly, the rectal temperature was also within the normal limits when
recorded at the first sign of recovery from anesthesia (Table 18).
In contrast to the observations made in the present study Chandrashekarappa,
(2004) reported that administration of pentazocine lactate, an opiod analgesic as a
preanesthetic agent followed by Propofol anesthesia in dogs resulted in a significant drop
in rectal temperature throughout the period of surgery. However, Romafidine another
preanesthetic agent when used prior to induction of anesthesia with thiopentone in dogs
was reported not to significantly affect the rectal temperature prior to, during and after
surgery (Nageshappa, 1999).
The reduction in rectal temperature following premedication and induction of
anesthesia as reported by Chandrashekarappa, (2004) has been attributed to its depressive
effects on thermoregulatory center along with decreased metabolic rate and reduced
skeletal-muscle activity (Goodman and Gillman, 1980; 2001). In the present study, the
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period of recording of rectal temperature was done only thrice, once prior to
premedication, again prior to surgical incision and finally at the first sign of recovery and
in most of the animals the time lapse between administration of premedication to first
sign of recovery was less than 90 minutes and probably this time is too short for the
preanesthetic agents and the anesthetic agent to significantly alter the rectal temperature.
The heart rate and pulse rate in all the animals prior to sedation were within the
normal limits. However, there was a significant drop in the heart and pulse rate when
assed after the administration of premedication and induction of anesthesia irrespective of
the type of anesthesia used. However, the heart and pulse rates had returned to normal
rate at the first sign of recovery in all the groups (Table 19 and 20).
The significant drop in heart and pulse rate after the administration of
premedication and anesthesia has also been observed with Romofidine as preanesthetic
agent followed induction of general anesthesia with thiopentone (Nageshappa, 1999).
Other investigators have also reported a drop in heart and pulse rate following
premedication and induction of general anesthesia in dogs. Robert and Stephenson,
(1986) reported a significant decrease in heart rate during Propofol anesthesia in dogs.
The results of the present study confirm that all anesthetic agents have a
depressive effect on the cardiovascular function of the mother and possibly even the
fetus. It therefore becomes necessary that the anesthesia is monitored very closely and the
surgery carried out with a minimum dose possible and in shortest duration to avoid
cardiovascular depression.
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The respiratory rates in all the animals prior to sedation was within the normal
limits, but administration of preanesthetic agents followed by induction of anesthesia
caused a significant reduction in the respiratory rate irrespective of the type of anesthesia
used. However, the respiratory rates were within the normal limits at the first sign of
recovery from anesthesia (Table 21). The depressive effects of premedication and
anesthesia on the respiratory rates in dogs has also been reported by England et al.,
(1996), England and Hammond, (1997) and England and Watts., (1997). The depressive
effects of premedication and anesthesia therefore need to be kept in mind while
attempting cesarean section in dogs, particularly when the objective is to deliver live
puppies.
It has been reported that pregnant dams have decreased lung volume, decreased
functional residual capacity and increased oxygen consumption which predispose them to
arterial hemoglobin desaturation and lung atelectasis (Pascoe and Moon, 2001). Further,
changes in maternal respiratory and cardiovascular physiology that occur during
pregnancy have a significant impact on anesthetic pharmacokinetic and
pharmacodynamics (Pascoe and Moon, 2001). In view of the unique physiology of the
pregnant bitch which has a significant impact on the selection of the anesthetic protocol
for cesarean section in bitches, changes in certain hematological and blood biochemical
constituents were monitored in the present study prior to, after premedication and
induction of anesthesia and again following recovery from anesthesia. The hematological
parameters monitored were hemoglobin concentration, total leucocyte count and platelet
count.
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In all the animals irrespective of the anesthetic protocols to which they were
assigned, the hemoglobin, total leukocyte count and platelet counts were within the
normal limits (Table 22, 23 and 24). The hematological parameters exhibited a slight non
significant drop following premedication and anesthesia and a further non significant
decrease following completion of surgery. The mild decrease in the values of hemoglobin
total leukocyte count and platelet count recorded during and following the completion of
surgery might have been due to splenic pooling of blood during the period of anesthesia
and confirms the observation of Collettee and Meriwether, (1965). Similar observations
have also been reported by Sharma et al., (1983). It is also possible that the marginal
decrease in the hematological parameters recorded in the present study during and after
surgery is due to haemodilution as all the animals received an intravenous infusion of a
balanced electrolyte solution through the period of surgery and during the recovery
period.
The blood biochemical parameters monitored were serum ALT, BUN, Serum
Creatinine, Serum Calcium and Random Blood Glucose. The ALT, BUN and Creatinine
concentrations in all animals remained within normal limits prior to and until the first
sign of recovery from anesthesia (Table 25, 26 and 27). The concentration of these
biochemical parameters, however, showed a nonsignificant decrease during the course of
surgery which was probably due to haemodilution. Further, the results of the present
study also indicate that none of the anesthetic protocol had a significant effect on the liver
and kidney functions. Similar observations have been made by Chandrashekarappa,
(2004) with different anesthetic protocol.
124
The serum calcium concentration in all the 48 animals with dystocia and prior to
premedication and administration of intravenous fluids was found to be within normal
range (Table 28). Hypocalcaemia is commonly believed to be a cause of uterine inertia in
dogs and calcium is routinely administered by Veterinarians in an attempt to augment
uterine contractions, many a times without the proof that hypocalcaemia was the cause of
dystocia. The normal calcium levels observed in patients with dystocia in the present
study suggest that hypocalcaemia is not a major cause for uterine inertia in dogs and this
may explain why calcium administration is not always successful in correcting cases of
uterine inertia.
The serum calcium levels showed a nonsignificant drop following premedication
and anesthesia and a further nonsignificant drop by the time of recovery (Table 28). This
can probably be explained due to the effects of haemodilution and further reiterates that
the anesthetic protocols have no significant effect on serum calcium concentration.
In all the animals the blood glucose concentration prior to premedication and
anesthesia was significantly elevated (Table 29) as compared to the normal values for
dogs (60-125mg/dl). It is possible that animals with dystocia are in stress like condition
with increased release of glucocorticoids which in turn may be responsible for an
elevated blood glucose concentration. It is also possible that some animals may have been
infused with dextrose prior to the presentation at this clinic contributing to an elevated
blood glucose concentration. The blood glucose concentration however, remained at
higher levels throughout the period of surgery and during the course of recovery and thus
it seems that the anesthetic protocols have no immediate significant effects on the blood
glucose concentration.
125
The hematological and biochemical studies made in the present investigation
clearly indicate that these parameters are generally within the normal limits in healthy
animals carrying live fetuses and also suggest that the anesthetic protocol have little
influence on these parameters. However, the long term affects remains to be studied.
5.12.3.2 Evaluation of anesthetic protocols
In the present study, four different protocols namely Propofol, Propofol and
ketamine, Isoflurane and Epidural analgesia were evaluated for the ease of induction
skeletal muscle relaxation, time taken for recovery from anesthesia after surgery and
degree of cardio vascular and respiratory depression in the neonates (Table 30). It was
observed that the ease of induction of chemical restraint was best with intravenous
anesthetic solution namely Propofol and Propofol plus ketamine and was most difficult
with epidural analgesia as most animals struggled during this technique. Further, the
skeletal muscle relaxation achieved with a epidural analgesia was also very poor. In
addition, maintaining the animal in dorsal recumbency for surgery presented some
difficulties and the number of persons required to restrain the animal during the course of
surgery was also more with the epidural analgesia as only the posterior part of the body
was under analgesia. The animals also could not be carried easily as the animal remained
conscious and alert. Animals subjected to epidural analgesia also had a prolonged
recovery time. A positive aspect of epidural analgesia however, was that the neonates
delivered had a minimal cardiovascular and respiratory depression and majority of the
neonate born were squealing almost immediately after they were removed from the
uterus. As many as 97 per cent of the puppies delivered were live and the puppy mortality
rate was just around 03 per cent which was highly encouraging (Table 31). In human,
126
epidural techniques produced less neonatal depression compared to general anesthesia
(Rolbin et al., 1994; Ratcliffe and Evans, 1993). But, potential adverse effect such as
severe hypotension observed with this technique indicated that it is not perfectly safe
(Boyler, 1993).
The puppy survival rate with the other three anesthetic protocols namely Propofol,
Propofol plus ketamine and isoflurane ranged between 92.18 to 93.42 per cent. The
skeletal muscle relaxation was best with isoflurane and these animals also had the
shortest recovery time. However, the animals exhibited slight struggling at the time of
induction of anesthesia. Kaniko et al., (1993) have also reported that isoflurance
anesthesia resulted in a better puppy survival rate when used as an inhalant anesthetic for
cesarean section in bitches. Moon et al., (1998) reported that isoflurance was associated
with an improved neonatal survival rate.
With Propofol and Propofol plus ketamine anesthesia, although the ease of
induction and skeletal muscle relaxation were satisfactory, the neonates delivered had
some degree of cardio vascular and respiratory depression and in some cases took more
than one hour for the neonates to start squealing, although the puppy survival rate was
comparable with the puppies delivered following isoflurance anesthesia (Table 31).
Similar, observations have also been made by Seliskar et al., (2007).
Although, the present studies suggest that a satisfactory puppy survival rate can
be obtained with any of the four different anesthetic protocols used in this study, it seems
prudent to assume that at some point there are limits to this statement. Hence, a minimum
anesthesia time and a short duration between incisions to delivery will decrease the likely
127
hood of neonatal depression. To this end, the dam should be clipped and prepared for the
surgery prior to induction of anesthesia. If possible, the animal should be on the operation
table at induction and the surgeon should be scrubbed, gloved, gowned and ready to start
surgery immediately. It is essential to deliver only enough anesthetic as indicated by the
patient needs to provide analgesia with minimal fetal depression. All the four anesthetic
protocols used in the present study are equally satisfactory in terms of puppy survival
rate and the choice of anesthetic protocol will therefore will be dictated by factors such as
the familiarity with the technique (epidural), availability of equipment to administer
anesthetics (Isoflurane) and ease of the availability of anesthetic drug itself. Ketamine
and Propofol are presently extensively used in human obstetrics and are easily available
for veterinary use. It seems reasonable to recommend that most cesarean sections can be
carried out with confidence with either Propofol or a combination of Propofol and
ketamine anesthesia. A combination of Propofol and ketamine anesthesia is probably
superior to Propofol alone as Propofol when used alone needs to be administered
frequently because of its short acting nature which makes it expensive when used alone.
Summary
VI. SUMMARY
Studies were conducted to analyze the influence of breed, age, size and parity on
the incidence of dystocia in the bitch and on the frequency of various types of dystocia
and the efficacy of different treatment procedures employed to relieve dystocia. Studies
were also conducted to evaluate some of the anesthetic protocols used for cesarean
section in bitches with live fetuses.
The duration of pregnancy in 240 bitches with dystocia calculated as the interval
from first mating to the day of parturition ranged between 57 to 71 days with an average
of 62.16 ± 3.95 days. Further, it was also observed that only one third of the animals
presented with the complaint of dystocia had completed a gestation period. It was
concluded that the apparent variability in the length of gestation was probably due to the
tendency of the female to accept the male from 5-6 days before to 2-3 days after
ovulation and additionally variability may also be due to the prolonged survival of ova
and spermatozoa.
The gestational age in the same bitches determined by measurements of biparietal
head diameter also varied widely (59-69 days) and in only 27 per cent of the animals, the
gestational age were determined as between 63-65 days. It was concluded that
ultrasonographic measurements may not be accurate for estimation of gestation stage in
bitches due to their wide variability in the size of the breed. It is suggested to develop
standards on different breeds/classes of bitch to make it more effective.
The most common behavioral sign observed by the owner of the patient at the
onset of parturition were nesting, restlessness and panting. However, these signs were
129
observed only in 20-30 per cent of the animals suggesting that the behavioral signs
cannot be used with certainity to suggest that the animals are indeed in the act of
parturition. Nevertheless, they are useful symptoms to the owners to present the bitch for
examination and confirmation and thereby avoiding future complications.
Nearly 50 per cent of the animals with dystocia were presented with a history of
copious mucoid discharge with slight greenish tinge. In most animals exhibiting this kind
of discharge, the fetuses were found to be alive as identified by ultrasonographic
examination. In nearly 15.42 per cent of the animals, the vaginal discharges were dark
and blackish green and in another 33.33 per cent it was brownish and foul smelling
indicating that dystocia had existed for considerable period of time. It was concluded that
the nature of vaginal discharge in a bitch with dystocia may provide a clue regarding the
condition of the genital tract and may help in deciding the choice of treatment.
Nearly 30 per cent of dystocia cases presented were either in Labrador Retriever
or German Shepards and it was concluded that the higher frequency of dystocia recorded
in these breeds may be due to large population of these breeds in the area. However,
23.63 per cent of all dystocias encountered were in brachycephalic breeds like Pug, Bull
dog and Boxers.
The size of the breed was found to have a significant effect on the incidence of
dystocia, the incidence being significantly higher in medium and large size breed. The
medium and large size breeds were represented by 12 different breeds whose population
is significantly higher in the area of the study and it was concluded that the higher
incidence of dystocia in medium and large size breeds is more because of their large
population.
130
It was also observed in the present study that the incidence of the dystocia was
highest in bitches aged 2-4 years and gradually declined with the advancing age. Bitches
less than 4 years accounted for nearly 62 per cent of the dystocia cases suggesting the
preference of owners to breed animals at their younger age and with hold breeding in
aged animals.
In the present study 45.83 per cent of cases referred were primiparous and the rest
had delivered 1-8 times. The incidence of dystocia decreased progressively with increase
in parity and the least incidence was recorded in animals with more than 5 previous
deliveries.
In the present study all animals presented were in second stage of labor for atleast
2 hours and more than half the number of cases presented were in labour for atleast 8
hours. The high per centage of delayed presentations was possibly due to delayed referral
by the Veterinarian or due to negligence or ignorance of the owner.
In many animals with dystocia, the rectal temperature remained within the normal
limits inspite of prolonged duration of dystocia and in the presence of foul smelling
discharges and higher rectal temperature was invariably associated with history of
vaginal manipulation by the referring veterinarian. The mean heart, pulse and respiratory
rate in all 240 animals with dystocia were within the normal limits.
In the present study dystocia due to maternal causes were encountered in 63.34
per cent of cases and primary uterine inertia accounted for 63.15 per cent of maternal
causes of dystocia. Among the fetal causes of dystocia, deviation of the head was
131
encountered in more than 50 per cent of the cases. Further, forelimb flexion as a cause of
dystocia was encountered much more frequently than the flexion of hind limbs.
In the present study medical treatment using oxytocin, calcium and dextrose either
alone or in combination was employed to treat only cases of primary complete or primary
partial uterine inertia and the treatment protocol was successful in only 16.66 per cent of
the cases. Nearly 83 per cent of cases of primary uterine inertia failed to respond to
medical treatment and had to be subjected for cesarean section. The vaginal manipulative
procedures to relieve dystocia using gloved finger or sponged forceps was successful in
relieving 62.5 per cent of cases of obstructive dystocia and the rest had to be subjected
for cesarean section. Cesarean section had to be carried out in 63.75 per cent of all cases
of dystocia encountered in the present study. The higher frequency of cesarean section
employed to relieve dystocia in small animals may possibly due to small size of the
animal, multiparous nature, long duration of delivery and demands by the owner to
deliver as many live puppies as possible.
Although, cesarean section was carried out in 163 out of 240 cases of dystocia
presented during the course of the present investigation, the evaluation of different
anesthetic protocols were made in only 48 animals. All these animals were determined to
be carrying live fetuses and the cesarean section was the first choice of treatment as it
was determined that medical treatment and vaginal manipulative procedures were
unlikely to be successful in relieving the dystocia in these animals. The anesthetic
protocol evaluated were Propofol only, Propofol with ketamine, Isoflurane and epidural
analgesia.
132
Premedication with diazepam and administration of anticholinergic agent as well
as induction of anesthesia did not significantly influence the maternal rectal temperature,
which was monitored prior to and during surgery and at the time of recovery. In contrast,
there was a significant drop in heart rate, pulse rate and respiratory rate following
induction of anesthesia suggesting the necessity of anesthesia being monitored very
closely and surgery carried out with a minimum dosage possible and in shortest period to
avoid cardio vascular depression.
In all the animals, irrespective of the anesthetic protocol to which they were
assigned the hematological parameters namely the hemoglobin concentration, total
leukocyte count and platelet counts were unaffected by premedication and induction of
anesthesia, although there was a marginal decrease in these parameters during and after
surgery which was attributed to haemodilution as all animals received an intravenous
infusion of a balanced electrolyte solution during the course of surgery and during the
recovery period from anesthetic effect.
The blood biochemical parameters, namely serum allanine aminotrnasferase,
blood urea nitrogen, serum creatinine, serum calcium and random blood glucose also
remained unaffected by the anesthetic protocols used suggesting that the anesthetic
protocols employed in the present study did not significantly affect liver and kidney
function.
The ease of induction of anesthesia was best with intravenous anesthetic solution
namely propofol, propofol and ketamine and was most difficult with epidural analgesia in
which the skeletal muscle relaxation achieved was also poor and the animals had a
133
prolonged recovery time. However, the new borns delivered with dam under epidural
analgesia had minimal respiratory and cardiovascular depression and as many as 97 per
cent of puppies delivered were alive when cesarean was carried out under epidural
analgesia.
The puppy survival rate with the other three protocols namely, propofol, propofol
plus ketamine and isoflurane anaesthesia ranged between 92.18 to 93.42 per cent. The
skeletal muscle relaxation was best with isoflurane and these animals had the shortest
recovery period. The neonates delivered when cesarean section was carried out with
propofol and propofol ketamine anesthesia had some degree of cardiovascular and
respiratory depression although, the final survival rate was comparable with those under
isoflurane anesthesia.
It was concluded that propofol, propofol and ketamine and Isoflurane anesthesia
and epidural analgesia are all equally satisfactory in terms of puppy survival rate and any
of these protocols can be used for cesarean section in bitches. However, the choice of
anesthetic protocol may be dictated by factors such as the familiarity with the technique
(epidural), availability of the equipment to administer anesthetics (Isoflurane) and
availability of the drug itself. In view of the ease of administration, availability of the
drug and a satisfactory puppy survival rate propofol or a combination propofol and
ketamine anesthesia appears to be the best choice for cesarean section in dogs. Further, a
combination of propofol and ketamine anesthesia is probably superior to propofol alone
as propofol when used alone needs to be administered frequently because of its short
acting nature which also makes it expensive.
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Abstract
Annexure
150
VIII. ABSTRACT
Studies were conducted to analyze the influence of breed, age, size and parity on
the incidence of dystocia in the bitch and on the frequency of various types of dystocia
and the efficacy of different treatment procedures employed to relieve dystocia. Studies
were also conducted to evaluate some of the anesthetic protocols used for cesarean
section in bitches with live fetuses.
The most common behavioral sign observed at the onset of parturition nesting,
panting and restlessness. Nearly 30 per cent of dystocia cases presented were either in
Labrador retriever or German Shepards. The incidence of dystocia was significantly
higher in medium and large sized breeds and in bitches aged 2-4 years and was more
common in pluriparous bitches. Maternal causes of dystocia were encountered more
frequently than fetal causes. Cesarean section had to be carried out in 63.75 percent in all
cases of dystocia in the present study.
The safety of different anesthetic protocols for cesarean section was studied in 48
animals with live fetuses. The anaesthetic protocols evaluated were propofol only,
propofol with ketamin, isoflurane and epidural anesthesia. There was a significant drop in
heart, pulse and respiratory rate following induction of anesthesia suggesting the
necessity of anesthesia being monitored closely and surgery carried out with minimum
dosage possible and in shortest time.
On the basis of ease of induction, effect on hematological and biochemical
parameters, degree of muscle relaxation, time taken for recovery from anesthesia and
puppy survival rate, it was concluded that all the anesthetic protocols evaluated in the
present study were equally satisfactory for cesarean section in dogs. However, in view of
ease of administration, availability of drug and satisfactory puppy survival rate, propofol
or propofol and ketamine anesthesia appears to be the best choice for cesarean section in
dogs.
151
ANNEXURE I
Case No.: Group: Date: Breed: Age: Parity: Weight:
1. Previous history:
Complication of previous pregnancy: Complication of previous parturition: Chronic ailments if any: Treatment given if any:______________________________________________________ Dystocia relieved if any: Vaginal Manipulation : Medical treatment : Caesarean section : 2. Present History: Dates of mating if any: Duration of pregnancy: 1st mating : 2nd mating : 3rd mating : Time of start of labour : Number of puppies delivered if any : Delivery of puppies normal or induced by medical or vaginal manipulation: Time of delivery of last puppy : Number of puppies delivered so far: live: Dead: Status of vaccination Deworming: Nutrition: Home made/Commercial/both 3. Present examination General body condition: Good: Fair: Poor: Temperature:.............................Pulse:.....................................................Respiration ECG: Normal: Abnormal: If abnormal ECG diagnosis:____________________________________________________ Trans-abdominal ultrasound
Fetal age: Viability: Fetal distress:
Nature of vaginal discharges Mucoid : Greenish and mucoid : Hemorraghic : Foul smelling : Abdominal Palpation Uterus hard: Fetal fluids: Fetus easily palpable: Vulval examination: Relaxed: Not relaxed: Vaginal examination: Relaxed: Not relaxed: Fetal parts: Palpable: Not palpable in the vagina
152
If not palpable Endoscopic examination: Bag visible Not visible 4. Diagnosis Fetal dystocia : Over size : Abnormal presentation : Position : Posture Maternal dystocia : Primary uterine inertia : Secondary uterine inertia : Partial primary uterine inertia : Uterine torsion : Vaginal abnormalities : Vulval abnormalities 5. Treatment followed a. Dystocia relieved by vaginal manipulation : b. Vaginal manipulation and medical treatment : c. Medical treatment only : d. Medical treatment and Caesarean section : e. Caesarean section only : 6. Presurgical Temperature:.............................Pulse:.....................................................Respiration ECG: Normal: Abnormal: Haematological parameters TLC: Hb: PCV: Biochemical parameters
