Katie Scotter VetMB BA MRCVS, Molecare Veterinary Services
50% of losses occur before 48 hours of birth, with 30% due to abortion or stillbirth. The majority of abortions are caused by infectious agents, including enzootic abortion, toxoplasmosis, campylobacter, salmonella and listeriosis. Only 20% of abortions are due to other factors such as poor nutrition, parasite burdens of worms or fluke, and stress. We have an opportunity to control the infectious agents that cause abortion and significantly reduce lamb losses as a result.
Accurate recording of births, deaths and abortions is critical to allow timely intervention when losses get too high. It also allows you to benchmark yourself against other similar flocks and year on year against your own figures. Did an intervention you put in last season work or not? Was it financially beneficial? Some abortions in the flock are inevitable but if abortions/stillbirths reach more than 2% or you have many abortions over a short time period you should get your vet involved and begin investigating the cause.
The best samples to have ready for your vet is aborted foetus and placenta. This gives the best chance of reaching a diagnosis. Acting quickly in the face of an abortion storm allows control measures and possible treatments to be put in place to minimise losses in the rest of the flock.
If you notice after lambing that abortion rates are high we can still diagnose infectious causes in the flock retrospectively. Bleed 6-8 aborted ewes within 4 months of lambing to assess the presence of enzootic abortion and toxoplasmosis in your flock. Whilst this cannot affect losses this season, if disease is present it can direct vaccination and minimise losses for the next lambing season.
Even without knowing the cause of an abortion you can put control measures in place yourself to reduce disease spread. Any aborting ewe should be isolated away from the flock. Aborted material should be collected either for sampling or for disposal. Aborted material and contaminated bedding should be burned. The ewe should be marked and isolated until after lambing.
Fortunately vaccination is possible to protect against the two most common infectious causes of abortion; enzootic abortion and toxoplasmosis. Ewes should be vaccinated 3-4 weeks before tupping to give protection for that breeding season. A single vaccination offers long lasting protection.
Acting quickly to mitigate the effects of an abortion storm can save huge losses this year and in those following. Diagnosis of the cause and farm specific control measures will allow a targeted approach to minimise lamb losses and improve the health and welfare of your stock. Even small increases in lambs sold can improve margins on sheep farms and have an economic benefit.
For more information phone Molecare Vets on 01392 872934 or visit www.molecarevetservices.com