Mad cow disease. Cow suffering from mad cow disease or BSE (bovine spongiform encephalopathy). BSE is a disease of cows which causes extensive brain damage, leading to a lack of coordination, spasms and death. It is thought to have originated from the sheep disease scrapie when dairy cows were fed on offal containing the brains of infected sheep. Eating meat from affected cows is thought to increase the risk of developing the human brain disease Creutzfeldt-Jakob disease (CJD). CJD causes similar symptoms in humans as BSE does in cattle. It is thought to be caused by a prion, a virus-like protein strand. There is no cure.