Sheep scab has been a frequent diagnosis across the regions in recent weeks. The vets have been busy taking skin scrapes and blood samples, and the vet techs have been occupied with administering injectable treatments as well as dipping.
Our wonderful lab technicians are quick to identify the sheep scab mite, Psoroptes ovis, under the microscope when we take skin scrapes from actively infested sheep. The problem is, by the time the sheep are showing the classic signs of rubbing, fidgeting and wool loss, the infestation is already well established and the sheep have already suffered. They may have lost condition due to the discomfort. Not to mention the fact that the mites have been spreading unchecked amongst the flock (up to 60% of the flock can be infected before any clinical signs are seen at all!).
The sheep scab serology blood test allows us to detect sheep scab before clinical signs appear. This is particularly useful when buying in new animals.
Antibodies can be detected in the blood from 2 weeks after infestation with mites.
It is a flock level test – testing 12 sheep per group (or all of them, if fewer than 12) gives us the best chance of finding scab if it’s there.
When buying in new sheep, isolate them for at least 2 weeks before testing them with the sheep scab serology test. If they test negative, then you can be reassured that they are not bringing scab mites into your flock. Testing is cheaper than treating. By testing first, and not treating “just in case”, costs are reduced. Additionally, mites that are resistant to the injectable treatments are becoming more common, so by avoiding unnecessary treatments we preserve the efficacy of these drugs for when we really need them.
If newly purchased sheep test positive after their 2 week quarantine, then you must treat them before allowing them to mix with the rest of the flock, avoiding an expensive whole flock treatment. Treatment consists of either plunge dipping, or injection with a 3-ML product.
Please contact your vet or the dispensary team for further advice on sheep scab control.
Written By Bella Lowis, Veterinary Surgeon
