Bovine spongiform encephalopathy (BSE, mad cow disease) is a disease of the central nervous system that causes lesions in the animal's brain.
Clinical signs of BSE may include:
- Behavioral changes such as aggression or nervousness
- Abnormal posture
- Lack of coordination
- Inability or difficulty in rising or walking
- Decreased milk production
- Weight loss with normal appetite
BSE is always fatal, normally within two weeks to six months after the signs first appear. However, the animal may be infected from two to eight years before showing clinical signs. This time is called the incubation period.
There is no test for BSE in live animals; the only way to diagnose it definitively is to examine tissue from the animal's brain under a microscope for the telltale sponge-like lesions.