Shared Flashcard Set


sheep 2: perinatal lamb mortality
Veterinary Medicine

Additional Veterinary Medicine Flashcards




opportunities for improved animal health management

- lambing percentage 

- lamb growth

- ectoparasitism

- ill thrift in ewes

- lameness

- lamb deaths

- disease problems 

lambing percentage

number of lambs born and surviving until a definitive event such as marking or weaning per 100 ewes mated

- targets vary depending on sheep breed and production system

Events that determine the lambing percentage


  • Oestrusbehaviour.

  • Ovulation rate.

  • Fertilisation.

  • Conception.

  • Foetaldevelopment.

  • Foetalsurvival/abortion.

  • Ewe deaths.

  • Perinatal lamb mortality.

  • Lamb losses from 1 week old to weaning. 

perinatal lamb mortality

 - lamb deads within the first week after birth

- between 80 and 90% of lamb deaths occur during the perinatal period

- hard to quantify in hill and extensively managed flocks

- can calculate from the difference between scanning and docking/marking data 

- reducing perinatal mortality to 10% increases the gross margin  sufficient to enable the purchase of extra food, planting of shelter belts

Reasons for perinatal lamb mortality

- most newborn lamb deaths are a consequence of different combos

- under-nutrition of the pregnant ewe

- dystocia

- under-nutrition to the newborn lamb

lambs must be born mature, with adequate energy reserves free from birth stress, and receive adequate post partum nutrition


Pre-Partum nutrition

Severe maternal undernutrition during

mid pregnancy causes poor placental

pooroxygen,nutrient and electrolyte transfer

low lamb birth weights.
long term foetal hypoxaemia inhibits the new-born lamb’s capacity

for thermoregulation.

Maternal under-nutrition during the final six weeks of pregnancy results in the birth of hypoglycaemic lambs and in poor udder development and colostrum production.

  • Overfeeding of single-bearing ewes during late pregnancy can result in dystocia.

  • Lambs born to 55 60 kg ewes with birthweights below 3 kg and greater than 5.5 kg suffer the highest rates of perinatal mortality.
    - healthy lambs are born with limited energy reserves

     - in physiologically compromised lambs these reserves are depleted

    - starved lambs rapidly become hypoglycaemic


birth stress ( dystocia)


Compression of the umbilical cord, protracted labour or trauma to the foetal central nervous system.

short term, usually reversible hypoxaemia.

parturient deaths result .

Inhibited thermoregulation, teat searching and suckling behaviour.

soft tissue trauma occurring during parturition and subsequent infection may compromise maternal behaviour. 

Poor maternal pelvic conformation.

  • Foetaloversize.

  • Malpresentedlambs.

  • Unskilledshepherding.

  • Uterine inertia.

  • Vaginalprolapse.

  • Ringwomb. 

Maternal factors responsible for lamb starvation


  • Genotype-someindividualsand certain ewe breeds demonstrate poor mothering behaviour .

  • Inexperience-primiparousewes refusing to allow their lambs to suckle.

  • Undernutrition-resultinginpoor colostrum accumulation.

  • Dystocia.

  • Concurrentdiseases-suchas

    metritis or maedi-visna.

  • Mastitis.

  • Multiplebirths. 

    - multiple litters

    - prenatal malnutrition

    - hypothermia

    - infectious disease

Extrinsic factors responsible for lamb starvation

- high stocking density of lambing ewes- mismothering

- disturbance of lambing or newly-lambed ewes

- human interference

- absence of feed near to the lambing site

- exposure 

management practices to reduce perinatal lamb mortality


  • Any management practices which ensure correct nutrition of the pregnant ewe, avoidance of dystocia, and adequate early lamb nutrition, will enhance the survival of newborn lambs.

  • The relative importance and practicality of such practices differ between flocks; hence general advice may be inappropriate.

perinatal lamb mortality.

Management practices to reduce

Need to first investigate the primary cause(s) of perinatal lamb mortality in individual flocks.

problem history.
monitoring of nutritional adequacy.

postmortem examinations. 

Problem history


  • Ewe feeding throughout pregnancy.

  • Ewe body condition scores at mating

    and lambing.

  • Ram breed and selection.

  • Ewe breed and parity.

  • Lambing percentage.

  • Weather conditions and the provision of shelter during lambing.

  • The management of ewes at lambing .

  • The size, shelter and topography of lambing paddocks.

  • The provision of skilled labour at lambing.

  • The stage and estimated numbers of lamb losses.

  • Ultrasound scanning data ewe vaccination programmes

  • History of trace element deficiencies and supplementation regimens.

  • History of abortions.

  • Preventive treatments for other known disease problems. 

Systematic  post mortem examination of lambs as part of the investigation of high perinatal lamb mortality rates


  • Informationonthetime of death.

  • A pathological diagnosis

    • –  Dystocia.

    • –  starvation-mismothering- hypothermia.

    • –  stillbirth/abortion.

    • –  other specific problems.

  • From a number of necropsies, a pattern emerges.

  • Providesusefulinformationwhenplacedincontextby the disease history and clinical observations. 

post mortem examination of newborn lambs


  • Weigh lambs.

  • Examine the feet to determine if the lamb has walked.

  • Examine the umbilical cord for signs of blood clotting and desiccation.

  • Check the carcase for signs of meconium staining, trauma, swellings and other physical abnormalities.

  • Examine the brown fat around the kidneys and pericardium for signs of atrophy.

  • Open the abomasum to determine the presence of clotted milk.

  • Check for rupture of the liver capsule.

  • Examine the lungs to determine if they are inflated.

  • Check for subcutaneous oedema.

  • Examine the thyroid glands for evidence of enlargement and goitre

  • Examine the carcase for other evidence of sepsis or inflammation. 

interpretation of the post mortem findings


  • Average bodyweights, atrophied brown fat and absence of clotted milk in the abomasum hypothermia

    on the basis of the disease history, this might be attributed to poor ewe nutrition, poor mothering ability, or disturbance of lambing ewes.

  • Heavy bodyweights, submandibular oedema and/or rupture of the liver capsule dystocia

    on the basis of the disease history, this might be attributed to poor ewe pelvic conformation, poor sire conformation, or unskilled supervision of lambing ewes. 

management practices to minimise perinatal mortality



Ensure adequate maternal nutrition

  • –  nutritional management.

  • –  disease prevention.

  • –  keel mark and ultrasound data.

  • –  metabolic profiles.

  • –  pre lambing shearing 



    Avoid dystocia

    • –  ewe and ram selection.

    • –  use of keel marks and

      scanning data.

    • –  careful shepherding.

    • –  ewe feed management. 



      Ensure adequate early lamb nutrition

      • –  ewe nutrition.

      • –  avoid dystocia.

      • –  selection for mothering ability.

      • –  skilled supervision.

      • –  preparation of lambing kit.

      • –  selection of lambing paddocks.

      • –  provision of shelter. 



Rectal temperature 39 - 40 °C - healthy lamb exhibiting normal suckling behaviour.

Rectal temperature 37 - 39 °C - weak, still capable of following the dam and suckling.

Rectal temperature < 37 °C - initially ambulatory, weak and depressed, may stand with an arched back, hollow flanks and lowered head, sometimes sheltering close to the ewe’s udder, but is unable to suckle. Clinical signs rapidly progress to recumbency, coma and death. 

Treatment for hypothermia


Moderate hypothermia (37oC - 39oC) - dry thoroughly; ensure a colostrum or milk feed; return to ewe; supervise closely. Lambing buildings should be draught-free and all- round shelter should always be availab

le in outdoor lambing fields.
Severely hypothermia (<37oC): under 5 hours-old - dry thoroughly; warm to > 37 °C; give a colostrum feed at a rate of 50 ml/kg; warm to 39 °C; return to the ewe; monitor closely and check dam for milk supply, disease or poor maternal behaviour.

Severely hypothermia (<37oC): over 5 hours-old - inject intraperitoneal 20% glucose at a rate of 10 ml/kg; dry thoroughly; warm to > 37 °C; give a colostrum feed at a rate of 50 ml/kg; warm to 39 °C; return to the ewe; monitor closely check dam for milk supply, disease or poor maternal behaviour. 

- lamb heater

- stomach tube if necessary

Warming results in increased cerebral metabolism, which rapidly leads to convulsions, coma and death if the hypoglycaemia is not first corrected by intraperitoneal administration of glucose. Oral administration of fluids to hypothermic lambs causes regurgitation and inhalation asphyxia or pneumonia.


Supporting users have an ad free experience!