Scrapie
Scrapie is a fatal, degenerative disease that affects the nervous systems of sheep and goats. It is considered one of many transmissible spongiform encephalopathies (TSEs), which are related to bovine spongiform encephalopathy or "mad cow disease", like other spongiform encephalopathies, is believed to be caused by a prion.The name is derived from one of the symptoms of the condition, wherein flocks of affected animals will compulsively scrape off their hides against rocks or trees. The disease apparently causes an uncontrollable itching sensation in the animals. Other symptoms include excessive lip-smacking, strange gaits, and convulsive collapse.
Scrapie is infectious and transmissible among similar animals, and so one of the most common ways to contain scrapie (since it is incurable) is to quarantine and destroy those affected.
A test is now available which is performed by sampling a small amount of lymphatic tissue from the third eyelid.
Scrapie does not appear to be transmissible to humans.