As we think about restarting the flock calendar at tupping time, one of the important jobs that has to be done is getting abortion vaccines into our ewes in a timely manner. I thought it would serve as a good reminder here to review the whats, the whys and the whens of abortion vaccines in sheep
What diseases are we vaccinating against?
The top three most common infectious causes of ovine abortion in the UK are Enzootic Abortion of Ewes or EAE (Chlamydophila abortus), Toxoplasma
gondii and Campylobacter species. The order in which these rank can vary year to year but they remain the most prevalent.
Enzootic Abortion (EAE) is a highly contagious bacterial disease that causes late-term abortion and is spread by contaminated aborted material and discharges. Affected ewes tend to abort in the final weeks of pregnancy but are generally otherwise well in themselves. Disease can be brought into a flock by buying in latently (hidden) infected replacements.
Toxoplasma gondii is a protozoal disease that is spread in cat faeces. If sheep eat contaminated food, water or bedding they can become infected and abort, but disease cannot spread directly from sheep to sheep. Depending on when a sheep is exposed will determine the outcome. If early in pregnancy then we may just see an increased barren rate, if mid-pregnancy then she may resorb, if late pregnancy she may abort or give birth to small, weak lambs.
There are a few different species of Campylobacter that cause abortion in sheep. Disease is spread by infected faeces by carrier sheep or by wildlife vectors. Abortion storms can spread rapidly through a flock and generally speaking we see these 4-5 years post entry when immunity in a flock wanes.
It is important to note that all of these diseases are zoonotic (meaning they can cause disease in humans) and some of these can potentially cause miscarriage in humans, which is why pregnant women should avoiding handling ewes, particularly at the time of lambing.
Who do we vaccinate?
All flocks are potentially vulnerable to Toxoplasma, as a small amount of cat faeces can infect many sheep. Even if there are no cats on your farm, consider are there any neighbourhood cats and also the risk of buying contaminated straw or hay from other farms.
Flocks that are buying in replacements are potentially vulnerable to Enzootic abortion and Campylobacter, but wildlife can play a factor for the latter. A robust vaccination plan should be put in discussion with your vet to ensure your flock is protected, according to your flock’s requirements. Some of the vaccines we use are one dose for ewe’s lifetime, so annually we only have to dose replacements.
When do we vaccinate?
Some of the vaccines we use are live vaccines, which means they can interfere with pregnancy. The timing of vaccination varies depending on the vaccine given, but generally speaking doses need to be given at least a month before tupping. If you breed your own replacements it is advisable to think about your vaccine needs in the spring, as vaccine supply can be more stretched in the autumn.
Written By Charlotte Mouland Veterinary Surgeon
