Scrapie is the most common reportable disease of goats and sheep in the United States today. Scrapie is a difficult disease to diagnose and is always fatal. It can take up to six years or more for clinical signs to appear. Scrapie is in the same category as bovine spongiform encephalopathy (BSE), or “mad cow disease,” and chronic wasting disease (CWD) of deer and elk. There is no evidence that scrapie or CWD can spread to humans, either through consuming the meat or dairy products or by handling infected animals. Scrapie is a disease of both sheep and goats; however, it is rare in goats.
Transmission: Scrapie is believed to be spread primarily vertically through direct contact between breeding stock and their offspring. The cause is most likely a prion, which is a sub-viral protein particle. It is transferred through contact with the placentas or fetal fluids of infected dams. The prion first invades the lymph nodes and then the nervous system. The prior somehow takes over protein synthesis in the brain and sheets of abnormal proteins are produced, eventually causing the classic “spongy” appearance of brain tissue.
Clinical signs usually progress slowly over a period of one to six months and have not been seen in goats less than 2 years of age. Animals suspected to have scrapie may show changes in gait, tremors of the head and neck, behavioral changes, lip smacking, loss of coordination, increased sensitivity to noise, rubbing against fences or feed bunks, skin/wool biting, and progressive weight loss with a normal appetite. Genetic testing can be used in sheep to identify a scrapie susceptibility gene; however, such a gene has not yet been identified in goats. The disease is much more likely in black-faced sheep breeds.
Videos of clinical signs may be viewed and information on the eradication program is available at http://www.aphis.usda.gov/animal_health/animal_diseases/scrapie/