Keepers of sheep and goats need to be aware of a disease known as Scrapie. This is a deadly disease that was first diagnosed in the 1700's. All the details of the scrapie are still not fully understood, but it is caused by a Prion (an infectious agent made mostly of protein), that attacks the central nervous system. Technically speaking it is a TSE (Transmissible Spongiform Encephlopath), similar to one that causes Chronic Wasting Disease in deer, and BSE, also known as Mad Cow Disease, in cattle.
To date there are no known cases of Scrapie being transferable to humans as the result of eating an infected animal, or being around them. Scrapie does spread between animals, although the means of transmission are not fully understood.
Scrapie may be hard to diagnose as symtoms of scrapie also show in other problems seen in both sheep, and goats. It should be noted that scrapie is more common in sheep than in goats.
Infected sheep, or goats, will appear itchy, rubbing themselves on fences, trees, and feeders. At first sign of these symptoms, keepers should check to see if their animals are suffering from an infection of Keds (wingless flies), or mange (caused by mites), both of which will also result in an itchy animal. Itching may also be a result of shedding, particularly in goats, and hair sheep.
Animals will also been seen to exhibit excessive lip smacking and travel in an uneven manner, possibly even falling over or experiencing convulsions. They will frequently stand with their heads down (also seen by healthy animals in hot weather), or may appear to be hunched, and in distress. They will eat well but will lose weight (also seen in animals with worms).
The disease is always fatal, causing death within one to six months from the time symptoms first appear. It is possible that an animal can be infected with scrapie for years prior to actually showing symptoms.
If suspected, a veterinarian should be called to conduct a conclusive test. The veterinarian will take a sample from the third eyelid. In goats a test can be done on a the brain tissue of a dead animal. Scrapie is a slow developing disease, as such an accurate visual diagnosis is difficult, and it can easily be mis-diagnosed, particularly in younger animals. A necropsy (animal autopsy) will show affected animals to have holes in their brain tissue.
Since there is no treatment, or vaccination, producers must look at prevention. Some breeds are more susceptible to Scrapie. In sheep these are the Suffolk and Chevoit breeds, with the hair sheep seeming to be more resistant. Genetic testing for resistance has been developed for sheep, but not goats.
Stress, such as over crowding, and underfeeding, may trigger Scrapie to activate in infected animals and thus animals who were not showing signs, suddenly will.
Infected animals should be slaughtered immediately and disposed of. Laws and regulations in different areas may require the entire flock to be slaughtered.
It has been suggested that the prions that cause scrapie can live in the environment for years, so farms who have had problems should not continue with sheep or goats.
Practice of a "closed flock" is an important way not to introduce the problem where it has not been found.
Purchase new animals only from farms who are certified as "Scrapie-Free".
Scrapie is known in North America and the United Kingdom, and has not been found in New Zealand or Australia.
This disease should always be taken seriously. It is a reportable disease, at first signs of a suspected case, a veterinarian should be consulted.