Bovine spongiform encephalopathy (BSE), a fatal, infectious disease that degenerates the central nervous system of cattle. It might have evolved from scrapie, a similar disease that infects sheep and goats. In Britain, the practice of feeding cattle with the remains of other cattle not known to have been infected helped spread the disease in the mid-1980s. (Given how the meat packing industry treats them anyway, no wonder the cows are mad. )