BSE is a transmissible, slowly progressive, degenerative disease of the CNS of adult cattle. This disease has a prolonged incubation period in cattle following oral exposure (2 to 8 years) and is always fatal. BSE is characterized by abnormalities of behavior, sensation, posture, and gait. These signs are similar to those seen in sheep that are infected with scrapie. BSE is associated with spongiform lesions in the gray matter neuropil of the brainstem and neuronal vacuolization. Neither vertical nor horizontal transmission has been documented for BSE.

BSE was first recognized as a new cattle disease by researchers at the Central Veterinary Laboratory of the British Ministry of Agriculture, Fisheries, and Foods at Weybridge, England in November 1986.