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Hypothermia and Starvation in Michigan Lambs, ~

By J. S. Rook, DVMMichigan State University

Hypothermia and starvation account for nearly 30% of all pre-weaning lamb losses. The majority of these lossesoccur prior to 3 weeks of age and producers should realize that starvation and hypothermia account for 50% of alllosses during week one and on day one of life. Management practices greatly affect hypothermia and starvation rateswithin given flocks. In large flocks averaging 10-20% total lamb death losses, hypothermia and starvation may accountfor as much as 49% or as little as 2% of those losses. Producers and their veterinarians should routinely examinenumerous dead lambs to identify trends within a given flock and use this information as a basis for management deci-sions. Lamb loss patterns within a given flock will vary from year to year and, thus, mortality surveillance should bean ongoing process just as dynamic as are decisions concerning management. This removable series of color printsand accompanying narrative should help producers to identify the most common mortality problems affecting their flock.For most lambs, a quick gross postmortem examination can determine the cause of their death. In some cases it

\...../ may be necessary to send lambs or their tissue samples to a diagnostic laboratory for testing. All producers, and especial-ly women of childbearing age, should exercise caution while handling dead lambs. Wearing rubber gloves and notallowing pregnant women to handle aborted lambs or placenta is just common sense.

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Weigh the lamb to determine the ap-proximate death weight. Small newbornlambs are extremely prone to hypo-thermia because they chill more quicklythan larger lambs. Low birth weightlambs, that die from hypothermia andstarvation, may indicate a nutritional prob.lem in the ewes during late gestation.Older lambs that die of starvation andhypothermia may also weigh less due tosimple starvation. Death weights for these2- to 3-week-old lambs are often similaror less than typical birth weights for theflock. It is important to connect this lossof weight to the mothering and milkingability of the ewe. Did she own the lamb?Was she fed enough to milk properly?Mastitis? Blocked teat?Examine the external surface of the

lamb to give you an idea of what that lambwas doing before it died. Most starvationand hypothermia lambs die on day one.They are often thought to be stillbornlambs, and are tossed in the pile of "borndead" lambs, when this is often not thecase. Stillborn lambs generally are coatedwith thick mucus or bright orange-yellowfluid, have a wet, fresh looking umbilicalcord, and often are still covered withplacenta. The bright yellow mustard-colored fluid covering them is uterine fluidstained with the lamb's meconium(manure) and indicates a difficult birth.Also, look under the tail in the rectal areafor any evidence of scouring and checklegs for any indication of fractures orswollen joints. A quick check for majorcongenital deformities shouid also bedone. although these are rare.Check feet and navel on all lambs to

help determine the age of the lamb (ifunknown). Stillborn lambs have soft,rounded. clean soles. typical of newbornanimals. If manure is on the boltom of thefeet and the soles are worn, the lamb wasstrong enough to stand and was lookingfor nutrition and warmth. This is common-ly the case with newborn lambs that pro-ducers just find dead shortly after birth.These lambs were born alive and had achance to survive. The umbilical cord alsobegins to dry and shrivel shortly after birthand usually falls off between 3 to 10 daysof age. This will also help document ageif the time of birth is unknown.Routinely necropsy lambs no matter

how sure you are of the cause of deathsince routine examination allows you torecognize normal structures and findings.You will not be prone to miss things if yourexam is done the same way each time.Lay the dead lamb on its right side withthe head to your left and feet towards you.Grab the front upper leg in your left hand

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and lift up (away from the rib cage) cut-ting the skin under the armpit. thusreflecting the front limb away from you ex-posing the entire rib cage. Look for signsof bruising over the ribs as fractured ribsare a common result of trauma. Also lookfor signs of pale discoloration of the mus-cle which might indicate vitamin E andselenium problems or hemorrhage. Donot mistake injection stains (yellow LA200or white penicillin) under the elbow forabscesses as this is a common site for in-jections.Normal newborn lambs have a layer

of tan fat which follows the junction of theribs to the cartilage of the sternum andthe junction of the ribs with the spine. Thisfat is readily apparent in stillborn lambsbut totally absent in starvation animals.After necropsying starvation and hypo-thermia lambs, the comparison is obvi-ous-look for it.Next make a long curved incision

from front to rear through the cartilagejunction of the ribs and sternum and con-tinue the cut up across the abdomen tothe area just in front of the hip. Lift up onthe ribs and push them away from you(you may actually break the ribs at theirconnection to the spine) allowing all theinternal organs of the chest and abdomento be viewed like an oyster on the half-shell. Trim any skin or muscle in your way.Finalfy, make a cut through the back

of the muscles of the ham area to checkfor uneven, pale muscle discolorationcharacteristic in this area for white-muscledisease.With the lamb opened in a routine man-

ner, the diagnosis of hypothermia andstarvation and other common diseasescan now be easily made while askingyourself several questions.1. ARE THE WNGS NORMAL AND

INFLATED? This is the first importantquestion to answer. especially in lambsdying from hypothermia and starvationduring day one. If the lamb is stillborn, thelungs will be an even dark purple colora-tion throughout-much the same colorand feel as the liver. Normal aeratedlungs, however, will be spongy to thetouch and an even colored pink. Varia-tions in color and feel with dark purplefirm areas toward the bottom and front ofthe lungs with normal feeling spongy pinkareas toward the top and back might in-dicate pneumonia or some other causeof death.

Starvation and hypothermia lambsshould have normal lungs unless somecompounding problem exists. Pneu-monia is often found secondary to star-

vation problems so don't be surprisedto observe both problems in the samelamb.Hypothermia lambs that die very

shortly after birth may also have a smafl --Jamount of clear amber-colored fluid inthe chest.2. IS THERE FAT IN THE HEART

GROOVES? While looking at the lungs,cut through the heart sac and expose thebare heart muscle. Normal stillborn lambshave a good supply of tan fat in thegrooves on the external surface of theheart. This fat is lacking in starvationlambs who have metabolized it for energy.3. IS THERE MILK IN THE STOMACH

AND INTESTINES? Normal newbornlambs have a very large true stomachfilled with a clear mucus and smallrudimentary forestomachs. The absence.of milk in the abomasum or true stomachis common in hypothermia and starvationlambs. Normally, when a lamb nurses, themilk bypasses the forestomachs and goesdirectly to the abomasum where it formscottage cheese-like curds during diges-tion. Weak lambs tube fed by producersoften have fluid milk (lacking curds) pre-sent in the forestomachs and abomasum(since suckling did not take place) andsometimes the extreme upper portion ofthe small intestine. Milk in the fore-stomachs, lack of curdling and absence \......Iof milk in the lower intestinal tract indicatetube feeding as a last resort. Do not ruleout starvation simply by the presenceor absence of milk. The presence oflarge amounts of sltage. hay or grassIn the stomach of very young lambsmay also support starvation.4. IS KIDNEY FAT PRESENT IN NOR-

MAL AMOUNT AND COLOR? Kidney fatcolor and consistency is probably themost remarkable change occurring instarvation and hypothermia lambs. As youexamine stillborn lambs, look at the largeamount of light brown fat mother naturedeposits around the kidney. This fat actsas a source of energy for newborn lambsuntil they receive adequate nutrition. Asstarvation ensues the fat changes from alight tan color to a dark purple gelatinousmaterial (about the color of black cherryjello) as it is gradually metabolized forenergy. Kidneys in older starvation lambsare often totally devoid of any fat. In ex-tremely cold weather, when the starvinglamb requires lots of calories for heat pro-duction, this change in color may occurover the 3-12 hours preceding death. Inwarmer weather, starvation may occur "-/over several days and result in kidneyswhich are totally devoid of fat. If you lookclosely, a small gland known as the

adrenal gland is also more obvious inolder starvationlambs.The adrenal is nor-mally small and hidden under the renalfat just in front of and to the inside of thekidney. The adrenal enlarges to producemore cortisone-like products in responseto the stress of starvation and becomesmore obvious due to the lack of fat.Hypothermia and starvation lambs dyingvery early in life will not have obviousadrenal enlargement due to the acute-ness of their condition. Older starvationlambs may.Remember to check kidney fat on all

dead lambs to appreciate normalamounts and color, and avoid missingstarvation-related Infectious diseases.

ConclusionRemember that 50% of all Michigan

lambs. that were born alive and died dur-ing week one of life. died from hypother-mia and starvation. Approaching thenutritional, environmental and manage-ment factorscontributing to starvationandhypothermia after lambing has begun issimply plugging the dike. Think aboutyour operation and where changes couldbe made for next year.

Figure 1-Typical stillborn lamb positionedon Its right side and ready to be necropsied.Notice the yellow meconium staining andsoH rounded hooves commonly seen in still.born lambs.

Figure 2-Cut the skin under the lront legand fold the cut leg oller the back of thelamb. Next cut the cartilage Junction of theribs and sternum and continue this cutthrough the skin and muscle up the flank tothe point of the hlp.

Figure 3-Stillborn lamb. Atter cuttingthrough the rib cartilage, 11ft the ribs andpush them away from you, breaking the ribsat their attachment to the spine. This shouldopen the chest and belly cavity for easyviewing. Notice the dark purple non.inflatedlungs typical of a lamb which neverbreathed. Also, notice the straw-coloredmucus normally found in the newborn'sstomach and the large deposits of tan.colored fat surrounding the kidney. Inflatedlungs ot a lamb which had breathed wouldbe reddish-pink in color and spongy feelingcompared to these dark purple lungs whichare of similar consistency to raw liver.

Figure 4-Notice the normal amount andcolor of the kidney fat In a newborn lamb.ThIs tan fat selVes as an energy source dur-ing the first few days at life. Compare thisto the pictures ot sfalVation and hypother.mla lambs.

Figure 5-Non-lnflated lungs of a stillbornlamb. Areas of hemorrhage (dark purplespots) on the lung surface are commonlyobserved.

FIgures 6 & 7-Not;ce the normal amountsof tan fat covering the ribs and chestmuscles of a newborn lamb (figure 6). Com-pare this to the lack of fat cover In a 5-day-old stalVatlon lamb (figure 7).

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Figure 8-This picture illustrates the pro-gressive fat loss and color changes com-monly observed In hypothermia and stalVa-tlon lambs. In cold weather; progressionfrom the normal fat color and consistencyobserved in the upper left kidney to theblack cherry }ello color of the lower left orupper middle kidney may only span severalhours. Warm weather starvation lambs sur.'lIving several days may totally deplete thekidney at tat as observed in the kidney In thelower center row or on the far right.

FIgure 9-AII the components of hypother-mia and starvation are present. Notice thesharp, manure stained hooves Indicatingthat this lamb was up and walking. Noticethe Inflated lungs, empty stomach and in.testlnes and the typical color change in thekidney tat.

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Figure 10-Trauma lambs often show bloodloss into the chest or abdominal cavity. Thisis normally due to fractured ribs or rupturedlivers. Notice the clotted blood around theliver of this traumatized lamb.

Figure 11-Many lambs die from more thanone cause. Notice the fractured ribs andpunctured lungs typical of a traumatizedlamb. The owne~thought that this lamb hadbeen crushed. However, further examinationrevealed a starvation kidney and emptystomach. Starvation was the primary causeof death. Starvation underlies many traumaand pneumonia deaths.

Figures 12 & 13-Lambs dying from pneu-monia usually will have a sharp line ofdemarcation between normal (pink andspongy) and diseased lung tissue. The darkreddish-purple, firm diseased area is usuallylocated to the front and bottom of the lungswith the normal area usually positioned tothe top and back. This is obvious In bothfigures 12 and 13. Figure 12 shows the sud-den severe pneumonia that often occurs In1- to 2-day~old lambs. Figure 13 shows amore chronic condition with round, yellowabscesses distributed throughout the dis-eased portions of the lung.

The Shepherd sincerely thanks Dr. Joe Rook for aI/owing us to publish his slides onthe necropsy of lambs. With the assistance of dedicated veterinarians like Dr. Rook, thesheep industry may be able to defeat the scourges of lambing time, hypothermia andstarvation. We hope that our readers will make good use of Dr. Rook's work and thatit will aid them in diagnosing problems in their own lambing sheds. Again, our thanksto Dr. Rook.

Guy Flora, EditorThe Shepherd

THEG"s'iiEPHERDMagazine

Figures 14, 15 & 16-Abortlon causes areoften difficult to document. Figure 14 /I~lustrates the circular, doughnut-shapedareas on the liver sometimes noted withvibrionic abortion. Figures 15 and 16 arecommonly seen with toxoplasmosis abor-tion. Figure 15 illustrates a typical set oftwins aborted from toxoplasmosis. Noticethe mummified fetus and more normal look.ing twin. Figure 16 illustrates the white,granular appearance to the buttons of theplacenta commonly seen with toxoplas-mosis abortions.

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