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Farm Animal Practice
Infectious abortion in sheep
  1. David Buxton

    David Buxton is based at the department of pathology at the Moredun Research Institute in Edinburgh. He has worked on ovine toxoplasmosis for a number of years, as well as ovine chlamydial abortion, neuropathological conditions of sheep and diseases of farmed deer. More recently, he has started to investigate abortions of cattle caused by Neospora caninum.

  2. David Henderson

    David Henderson was head of the Division of Clinical Studies at the Moredun Research Institute in Edinburgh for 15 years before his retirement this year. He is currently chief executive of VETCPD Enterprise. He is a past-president of the Sheep Veterinary Society and author of ‘The Veterinary Book for Sheep Farmers’, published by Farming Press.


WHILE many organisms can cause sporadic, fatal infections of the ovine fetus, a smaller number have a particular ability to colonise the conceptus and cause characteristic syndromes of abortion. The aim of this article is to provide an update on infectious causes of abortion, focusing primarily on those that commonly occur in the UK. Of the protozoa, Toxoplasma gondii is a major cause of abortion in many sheep-producing countries, including the UK, while Sarcocystis species and Neospora caninum also have the potential to cause fetal loss. Of the bacteria, Chlamydia psittaci is the major pathogen of pregnancy in the UK, as in parts of continental Europe; Campylobacter fetus fetus, Salmonella species, Listeria monocytogenes and Brucella melitensis can also cause severe losses, although the last does not occur in the UK. The rickettsia Coxiella burnetii probably infects the ovine placenta more often than is recognised, though fetal death is relatively uncommon, while abortion due to tickborne fever is secondary to the febrile response. The most important viral infection in the UK is border disease; Wesselsbron disease, bluetongue and Akabane virus disease occur outside the UK. All may attack the ovine fetus, damaging the developing central nervous system and sometimes also other systems such as the skeleton.

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