A transmissible, usually fatal disease of adult sheep characterized by degeneration of the central nervous system. The disease is known in Great Britain, France, Belgium, Iceland, the United States, Canada, and northern India. Scrapie has certain similarities with kuru, a human disease in New Guinea, and mink encephalopathy. Scrapie affects both sexes and is insidious in its onset, starting with hyperexcitability and progressive itch. Later, loss of wool occurs when the animal rubs against fixed objects or bites and nibbles its skin. Some animals do not rub but are either nervous and tremble when approached or appear sleepy. Incoordination of gait is constant and usually more evident in the hindquarters. In the final stages the sheep, being unable to stand, lie down, become emaciated, and die. Prion disease |
