Our practice has had some cases of sheep aborting in recent weeks, mainly in pedigree lambing flocks where early lambing is popular.

One recent case involved a hogget delivering two malformed lambs which were premature and partially decomposed.

The other ewe presented with a waterbag protruding from a prolapsed vagina, with incomplete dilation of the cervix.

This meant that the ewe had to have a caesarean section, resulting in the delivery of two weak lambs which, while born alive, died before the ewe’s operation ended.

In both cases, we took samples from the ewe’s placenta and the surface of the lamb. The placenta samples were taken by rubbing a cotton swab on a placental cotyledon (button). A separate sample can be taken from the fluids on the surface of the lamb.

The samples were tested using PCR. This test can identify low levels of infectious material. The sample from the first hogget tested positive for toxoplasmosis, while the ewe had been infected with enzootic abortion (EAE).

This method of testing differs from a blood sample, as it demonstrates the presence of the actual abortion-causing organism in the ewe’s uterus, rather than demonstrating the ewe’s immune response .

Toxoplasmosis is a parasitic disease which can be spread by cats. Therefore, ewes aborting due to toxoplasmosis are not directly infectious to other ewes. On the other hand, EAE is contagious and early identification can help by ensuring aborted ewes are kept isolated and allow for the preventative use of antibiotics in at-risk comrade animals.

However, as with any disease, antibiotics should not be relied upon for long-term control.

Early, accurate diagnosis of infectious abortion in ewes can help in the management of the disease and the selection of appropriate vaccination programmes.

John Gilmore is a practising veterinary surgeon and managing director of FarmLab Diagnostics, an animal health testing laboratory, www.farmlab.ie, in Elphin, Co Roscommon.