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Infectious Causes of Abortions in Sheep

Expect an infectious cause if >2% of flock aborts.

Diagnosis of abortions

  • Submit fetal tissues, blood from dam, placenta.

Best management practices

  • Isolate all aborting females.

  • Improve nutrition to all.

  • Be sure all feeders are elevated.

  • Treat females with tetracycline if warranted under veterinary care.

  • Completely dispose of all materials associated with aborted births and normal births, including dead lambs by incineration or land fill.

  • More than one agent or cause may be active at one time.

Possible Causes

Chlamydiosis-EAE Enzootic Abortion of Ewes

  • Caused by Chlamydophila abortus

  • Acquired at birth, from aborting ewes, intestinal carriers and venereal spread.

  • Will abort at next pregnancy.

  • Abort in last two to four weeks of pregnancy.

  • Fetus can be fresh, autolyzed, or weak alive.

  • Zoonotic disease.

  • Placentitis

  • Vaccine available, flock treatment available. Consult with veterinarian.


  • Caused by Campylobacter fetus or C. jejunum
  • Spread by carrier ewes in endemic flock and possibly by birds.
  • Abort last 4-6 weeks
  • Fetus will be autolyzed. Placenta will be normal.
  • Vaccine available.


  • Caused by Toxoplasma gondii
  • Ingestion of oocysts of parasite in cat [kitten] feces.
  • Abort any stage of pregnancy.
  • Mummification-think toxo first.
  • Mummification, resorption, stillbirths, infected weak lambs.
  • Placenta will have white 1-3 mm foci in cotyledons.
  • Can use serology to diagnose.


  • Caused by Listeria monocytogenes
  • Likes cold and dark to grow. Grows in spoiled silage.
  • Fetus is septicemic
  • Causes retained placenta and metritis.


  • Caused by any Salmonella species
  • Causes abortion, stillbirths, weak neonates.
  • Ewe will be sick. May die.

Q Fever

  • Caused by Coxiella burnetii
  • Organism can be shed in placenta and birth fluids at normal parturition
  • Causes abortion in the last 2-4 weeks
  • Fetus will be autolyzed
  • Placenta will be thick.
  • Can be treated with antibiotics.


  • Caused by Brucella ovis
  • Usually causes ram epididymitis
  • Causes a few abortions, stillbirths and weak lambs.
  • Have about 20% smaller lamb crop.
  • Results in longer lambing period.
  • Causes placentitis.


  • Caused by Leptospira species
  • Can be in urine contaminated water or food.
  • Causes late gestation abortions with autolyzed fetuses.
  • Causes nephritis, hemoglobinuria in the ewe.
  • Also agalactia and infertility.


  • Caused by Sarcocystis sporocysts in canine feces.
  • Aborting ewe is clinically ill.

Cache Valley Abortion

  • Caused by Bunyanviruses

  • Has Culicoides and mosquito vectors

  • Causes abortions, mummifications, arthrogryposis, hydrancephaly, December and January lambings.

  • Can diagnose with serology

This material taken from Dr. Mary Smith's Infectious Abortions in Sheep and Goats - Sheep and Goat Medicine - 2014.