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Diagnosing
pregnancy losses

Diagnosing
Investigations
Sheep

Diagnosing Pregnancy Losses

Pregnancy losses after pregnancy diagnosis in healthy sheep are normally low (<2%), however rates can reach up to 30% or more. When high abortion rates are observed it is likely to be due to a pathologic process.  Your local veterinary practitioner or district veterinarian can assist with investigation and testing to diagnose pregnancy losses.

Sheep

Common causes of pregnancy losses include:

Vibrionic abortion, cause by Campylobcter fetus or Campylonacter jejuni

Enzootic abortion, caused by Chlamydophila abortus

Toxoplasma abortion, caused by Toxoplasma gondii

Salmonella abortion

Leptospirosis

Coxiella burnetti  (Q fever)

Brucellosis

Listeriosis

Border disease

Caprine herpesvirus 1

Vibriosis, caused by Campylobacter fetus subsp fetus or Campylobacter jejuni

Causes sporadic abortion in the high rainfall regions in southern Australia. Susceptible ewes are infected by ingestion of contaminated pasture, water or feed that has been contaminated by aborted foetal fluids, foetuses, placenta or contaminated faeces. Once ingested, the bacteria spreads to the uterus of pregnant sheep where it multiples resulting in placentitis and subsequent abortion.

Toxoplasma abortion, caused by Toxoplasma gondii

Toxoplasma gondii is a protozoal parasite. Domestic cats shed the infective ooctyes in their faeces. Sheep become infected when they ingest feed and water contaminated by cat faeces. Infection in early pregnancy can result in fetal death or birth of weak lambs. Infection during late pregnancy can lead to abortions or birth of weak lambs.

Salmonella abortion

Multiple species of Salmonella have been responsible for causing abortion in sheep but abortion secondary to Salmonella typhimurium is most common. Ewes become infected when they ingest the bacteria which can enter the flock through asymptomatic carrier sheep or the contamination of feed and water by birds or other mammals. Most infected ewes become dull, lethargic, inappetant and febrile prior to aborting.

Leptospirosis

Leptospirosis occurs in sheep and is caused by bacteria called Leptospira. The disease is spread by urine from infected animals contaminating pastures, water and feed. Clinical signs in sheep can include; anaemia, jaundice, red water and abortions.

Coxiella burnetii (Q fever)

Coxiella burnetii can cause abortion in sheep and goats. The organism is present in high concentrations in the placenta, foetal fluids, urine and faeces of infected animals. Q fever has significant implications for human health.

Brucellosis

While the common manifestation of Brucella ovis is contagious epididymitis and subsequent infertility in rams it can also cause early embryonic death or late term abortions and stillbirths in ewes and the birth of weak non-viable lambs. B.ovis results in placentitis.

Listeriosis

Listeria sp can cause a wide range of disease in sheep including encephalitis, gastroenteritis, meningitis, septicemia and abortions. Listeria monocytogenes and L. ivanovii are the most common species encountered in ovine abortions. Both species are ubiquitous in the environment, however, they are most commonly seen in cold wet weather in animals grazing spoilt, decomposing plant material or being fed poorly fermented silage. Abortions generally occur in the last trimester of gestation.

Border Disease

Border disease is caused by a Pestivirus infection of the foetus in early pregnancy. Infection of naïve, pregnant ewes can lead to placentitis, foetal death, and abortion. Affected lambs are born 2-3 days prematurely and many die before or at weaning.

Diagnostic Investigations

Investigation of any abortions on farm can be useful to determine their cause. It is essential to contact your veterinarian or veterinary diagnostic laboratory to get advice. Record keeping is essential for:

History of the herd/flock and the disease outbreak 

Vaccinations given

Any addition of new animals to the herd

Symptoms

When collecting samples it is very important to wear personal protective equipment including gloves, eyewear and overalls.

Further Reading

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