Advertorial AUGUST 2018 Abortion in sheep Vet Suzanne Naughton from MSD Animal Health examines causes of abortion in sheep Many farmers commonly accept barren ewes and abortion rates of between five to ten per cent. However, anything above two per cent is likely due to an infectious disease and seriously warrants an investigation to determine the cause. Submission of aborted foetuses as well as samples of placental material to the regional laboratory is essential in aiding diagnosis. Blood samples taken from aborted or barren ewes can also give an indication of recent exposure to any potential abortion causing disease. Blood sampling can be carried out anywhere from three weeks up to three months after the abortion event. The most commonly diagnosed causes of abortion in sheep are toxoplasmosis and enzootic abortion (EAE). Other infectious agents which can be implicated in abortion outbreaks include salmonellosis, leptospirosis, listerosis and campylobacteriosis. Toxoplasmosis Toxoplasmosis is transmitted to sheep through the ingestion of feed and forage contaminated by infected cat faeces. A single cat dropping can contain enough eggs to infect more than one hundred ewes. Clinical signs depend on the stage of pregnancy during which the ewe is infected, and can include one or all of the following: barren ewes, mummified lambs, abortions and the birth of weak lambs. Typically, in chronically infected flocks, the abortion rate will be highest in the ewe lambs/hoggets while in newly infected flocks, having had no history of exposure, all age groups can be affected. 8