To understand what happens to cause parturition and what happens during and after parturition.

To understand the hormonal control of parturition.

To understand retained placentas, artificial induction of parturition and uterine involution.

Learning Objectives

How Was Mechanism For Parturition Discovered?

Skunk Cabbage - Sheep consuming this type of vegetation in western US had prolonged gestations. Fetus had congenital hypoplasia of Anterior Pituitary

Gene Defect - Autosomal recessive gene in Holstein breed Large calves grow in utero 1-2 months beyond delivery date. Congenital hypoplasia of Anterior Pituitary

Corn Lily(Vertatrum californicum)

Sheep Cyclops

FetusLamb

Pictures courtesy of USDA Poisonous Plant Research Lab in Logan, UT. Richard Davies and Robert Poppenga;University of Penn School of Veterinary Medicine Computer-Aided Learning Project

Initiation and Control of the Parturient Process

Hormonal Changes that Control Parturition

Time of parturition iscontrolled by maturation of the hypothalamus- pituitary-adrenal axis

CRFFetal anteriorpituitary gland

Stimulates oxytocin receptorin myometrium

Steps Fetal ACTH causes - Fetal Corticosteroids causes - Progesterone levels placental production or CL regression) - Production of Estrogens by placenta - PGF2production by

uterus - Pine-needle abortion incattle - cause by a corticosteroid-like product

Corticotropic ReleasingHormone

Infusion inducesparturition Fetal

Adrenal

AdrenalcorticotropicHormone (ACTH)

Removal Blocks Parturition

Corticosteroid

Glucocorticoid

Estrogen(Increase)

Progesterone(Decrease)

ProstaglandinF2

(Increase)

Hypothalamus

Redrawn from Liggins, G.C. 1969. In Foetal Autonomy

Mare

The day of parturition may occur through corticosteroidsbut the time (minute) of the day is regulated by the releaseof oxytocin from the mare.

Hormonal changes cause:

1.

2.

3.

4.

5.

6.

Final maturation of fetus

Expansion of birth canal

Maternal behavior

Synthesis and ejection of milk

Initiation of uterinecontractions

Termination of pregnancy

Initiates parturitionand lung development

Cortisol - stimulates lung surfactant

Prolactin completes finalmammary development and milk secretion

Fescue toxicity problems:Ergot causes inhibition ofprolactin release and thusmilk production

Significance of initial hormonal changes

Progesterone - removes block on uterine contractions.

Estrogen - makes uterus more responsive to induction of contractions i.e., more irritable and smooth muscle tissue stimulation.

Events just Prior to Parturition:

1. Pelvic ligaments soften - Tail head sinks due to estrogens and relaxin. 2. Cervix softens and begins secreting stringy mucus - estrogens and relaxin.

.

Allows myometrial muscle fibers to work together in bundles

Induction of oxytocin receptors

Increased water content in cervical tissue andcervical plug is removed

3. Swelling of vulva.

4. Udder swells - fills with first milk and due to edema:

5. Fetus moves into proper position - resting on thorax, front feet and head facing the cervix

Collagenase breaks down collagen which also widensthe pelvis

Prolactin, Estrogens and glucocorticoids

Stages of Parturition:

I. Dilation of Cervix. (2-6 hours, cow) Uterine contractions become coordinated and regular - Estrogen & PGF2 induced

Fetus pushed against cervix - amnion dilates cervix Chorioallantoic membrane may break

Pressure of fetus in cervix stimulates oxytocin release and reflex contractions of abdominal muscles.

Heifers 12 hours

SynchronizedThis occurs because progesterone has declined

Stimulates oxytocin release

1st Water Bag

Ferguson Reflex

Contractions force the calf legs and head tospread cervix

II. Expulsion of Fetus (.5-2 hours, cow) Strong uterine contractions due to synergistic actions of high estrogen, PGF2 and oxytocin Strong abdominal muscle contractions

Amnion ruptures - mucin lubricates vagina - vestibule

Fetus passes through vagina - vestibule.

Longer than 2 hours considered to have dystocia

2nd Water Bag

Cause of death in 6.4% of calf losses on average

1. Head

2. Shoulders

Three Barriers in Delivery of a Calf

3. Hips

Sow Delivery of Piglets

Length of Stage II in sow is 2 to 4 hours

Delivery of piglets is usually between 8 to 45 minutesbetween each one.

Delivery will alternate piglets between horns

Last 1/4 of horn in large litters increases the chanceof stillborn - Length of umbilical cord

Uterine horn contracts to shorten distance after deliveryof each piglet

III. Expulsion of the Placenta (4-5 hours, cow) Uterine contractions continue

Blood forced from cotyledon villi - shrinkage separates cotyledon and caruncle

Contractions push placenta out

Causes of retained Placentas: -Infections caused adhesions between cotyledon and caruncle

-Calving stress - twins or calving difficulty - edema of cotyledon - won't separate from caruncle -Weak uterine contractions - villi won't shrink

Prolapsed uterus -cow tired need to giveoxytocin

Oxytocin

Milk fever - Calcium low

Care of retained placentas:

Do not manually remove from uterus; uterine damage greater than infection of retained placenta

Infuse Bovine uterus with tetracycline and systemic injections of penicillin until placenta passes ~ 2-4 days.

Do not pull placenta out even in Mare!Check to see placenta is fully intact in Mare or you need aVeterinarian to clean her out.Don’t breed on foal heat if there is a problem

Don’t give mare tetracycline as this will cause inflammation!!

Can treat cow with either PGF2 or oxytocin (ergonovine)to expel the infection

Preventing retained placentas:

Vaccinate for Brucellosis and leptospirosis Make sure Vitamin A, E and Selenium are not deficient in diet

Don't have cows over-conditioned at calving

Have sanitary calving conditions

Allow heifers to be large enough at calving and don't breed to bull that sires larger calves than your female can handle.

Size of pelvisFeed and develop heifers before breeding

Uterine Involution:

Cow passes lochia - 1 to 2 weeks after birth. (mucus, blood, fetal membranes and surface of caruncle).

Caruncle regenerated by ~ 30 days post calving

Uterus completely involuted by 45 days postpartum

Shrinking of uterus due to muscle contractions

Involution enhanced by: suckling oxytocin release by estrus periods estrogen.

Foal heat 10-15 days postpartum in mare can have good fertility if there are no problem with of involution.

80 -90% done by Day 6

Sows can express a heat 7 days post-partum - Howeverthere is no ovulation with it

Artificial Induction of Parturition:

Reasons: Time parturition to labor costs

Avoid dystocia (Large Fetus)

How to do it:

Give ACTH

Give Corticosteroids. (Dexamethasone)

Give PGF2

Give Oxytocin

Need to know status and size of fetus

Must have Management First!Must Know Breeding Dates!!!

Cow - Do not induce before last 7-14 Days of gestation

Method: Dexamethasone - parturition in 48 hours, 20-50 mg/IM

-High incidence of retained placentas and lower postpartum fertility.

Azium (trade name) combined with 25 mg Lutalyse induces within 35+2 hours. Requires a live fetus work, does not work on a mummified fetus

If cow are induced earlyRetained placenta is not problem if treated properly- Giving estrogen before induction of parturition incidence

Prostaglandins used in cases of a mummified fetus and are also effective in inducing abortion the first 4-5 monthsExample for inducing parturition in beef cattle:Sixty breeding season, induce cows 265 days from lastday of breeding season

Sheep - Best within a few days of parturition

Dexamethasone (8-20 mg) Parturition in 24-72 hours

5 to 7 days

Retained placenta not a problem

Can use Lutalyse to abort before Day 50 of gestation

Goat - CL is important throughout pregnancy

Can use Lutalyse to induce 5-7 Days prior to normal time of parturition

Sow - Do after day 111 of gestation

PGF2 (Lutalyse 10 mg/IM) parturition in 29-48 hours.

Note that this is less than 3 Days from normal parturition

Close synchrony - Lutalyse at 8 AM followed by oxytocin 40 IU 24 hours later. Sows farrow between 8 AM and 5 PM (32 hours from start)

Piglets should be born within 1 to 8 (average 1-4) hours with15 minute intervals between piglets - May give oxytocin in last few piglets to decrease stillborn numbers in large litters or after extended delivery interval

Its is important to give PGF2 no sooner than Day 111. If given on Day 110 will cause stillborn piglets ( too immature to survive)

Mare - Do after day 320 of gestation Oxytocin (20-60 I.U.) close to term !!!

Takes less than 1 hour!Placenta expelled in < 1 hour

Make sure of the following before inducing foaling:

1. Udder is enlarged with presence of colostrum2. There is relaxation of the perineal region3. Cervical relaxation (can insert 1 to 2 fingers)

Usually induce for only two reasons: 1. Demonstration 2. Prolonged gestationIn normal pregnancy, mare can control time of day for foalingthrough her release of oxytocin. Inject oxytocin give no choiceof time.

Bitch

- If needed to get rid of unplanned mating

Give Prostaglandin F2 at:

.25 g/kg body weight 3X/day for 3 to 4 days

Induction of Abortion in Feedlot Heifers

1. All females in a feedlot should be examined rectally for pregnancy, and abortion induced at that time.

2. Animal induced to abort should be in good health and well adjusted to the feedlot. One should always remember, abortion will be stressful and combined with any other stress (diseases like shipping fever, pneumonia, etc.) can cause extreme losses in gain efficiency or even death.

3. Growth promotants containing progesterone or analogues to progesterone may interfere with induction of abortion and should be withheld until after abortion occurs.

Procedure:1. Heifers that are less than 150 days into gestation can be aborted with a single intramuscular injection of 25 mg Lutalyse or 500 g Estrumate Efficiency of 90%. 2. After 150 days of gestation, combination of 25 mg Dexamethazone and 500 g Estrumate is needed to cause abortion. Efficiency of 95%.

3. Abortion will occur over 2 to 10 days.

4. All abortions should be recorded, and heifers which fail to abort re-examined.

5. Failure to induce abortion is most likely caused by failure of luteolysis. Re- treatment will usually cause abortion.

6. In the case of fetal mummification, Prostaglandin treatment will stimulate expulsion.

7. Cows over 4 months pregnant will have a high percent of retained placenta (80%). Most cases will resolve themselves, but the producer needs to

monitor health of females after abortion.