Investigating lamb losses

Tablelands Telegraph – August 2021

Bruce Watt, District Veterinarian

Over the past month the veterinary team has taken numerous calls from sheep producers who have discovered stillborn lambs in the paddock or the yards. We perform a post-mortem on a sample of these lambs and usually submit samples to the laboratory to help us reach a diagnosis.

One cause of abortions that we have found recently is a bacterium known as Listeria. Listeria is quite a common cause of abortions in ewes, and occasionally causes abortions in cows and goats too. It usually occurs when sheep (and cows and goats) have access to wet, decomposing vegetation, quite possible this year. Listeria can also affect people and is most dangerous for pregnant women and people with a poor immune system. We ask that farmers continue to collect and dispose of the foetuses, but to use gloves and take great care with hygiene.

Toxoplasma also occasionally causes abortions in ewes. It is a parasite of cats, but if cat faeces contaminate feed or the pasture (the spores survive well in wet conditions and in water) then ewes can become infected, aborting their lambs. Toxoplasmosis is an important cause of ewe abortions in New Zealand and so they have a vaccine for it. As it is less of a problem here, a vaccine is not currently available.

Fortunately, abortions in ewes are generally not a major problem, but occasionally they can cause distressing losses. While we generally caution sheep owners that we find the cause of abortions in less than half the cases, we advise that it is important to investigate because some losses can be managed and prevented in the future.

Some of the bacteria that cause ewe abortions are important exotic diseases. These include Brucella melitensis which is both exotic and an important cause of illness in people overseas. It is acquired when people consume milk or cheese from infected sheep and goats. Chlamydia abortus is also an exotic disease that is the major cause of sheep abortions in Europe.

Contact your local District Vet if you have concerns about still born lambs.

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