Sheep Scab is an extremely contagious, parasitic disease caused by the mite Psoroptes ovis. The adult mites live in the fleece and cause an allergic reaction that can lead to intense itching by affected animals. This often presents as rubbing & scratching against fence posts and nibbling and biting of the fleece.

Particular clinical signs to watch out for include:

• dirty areas of fleece from scratching hair, especially behind the shoulder
• clean areas of fleece, where sheep have nibbled
• broken areas of fleece on the sides of sheep from biting and scratching

During the early stages on infection animals can appear clinical normal, it can take up to 40 days before signs of itching can show up. The intense itching found in the later stages of the disease leads to reduced feed    intakes and therefore loss of condition. In severe cases, large sections of fleece are rubbed off and is often accompanied by secondary bacterial infection of skin lesions.

Correctly diagnosing sheep scab is important as there are some other parasites such as lice that cause similar clinical signs but require slightly different treatment methods. Diagnosis can be achieved by looking at skin scraps under a microscope to identify the mites present. Blood samples can also be taken to look for antibodies against the mite. This is especially useful when animals are in quarantine before introduction to the main flock.

The two treatment options available are plunge dipping with an        organophosphate or using an injectable wormer from group 3 wormers such as Ivermectin. As the mites can survive in the environment for several weeks, animals may need a second wormer treatment depending on which product was used. We are always happy to discuss treatment options so give us a call at the practice with any questions.

Even though Sheep Scab is no longer a notifiable disease, there is a legal requirement to treat animals that are suspected to be infected.

Prevention of Sheep Scab is centred around good biosecurity practices. Maintaining a closed flock is a good strategy for prevention, whenever animals must be brought in, quarantining away from the home flock is strongly advised. As mentioned above, blood sampling for antibodies can be done at this stage.