Mad Cow DiseaseThe common name for Bovine Spongiform Encephalopathy (BSE), mad cow disease is a disease which causes the brains in cattle to waste away. It takes about 4-7 years for cattle to show symptoms of mad cow disease after being exposed to it, but once symptoms become visible the cattle die within weeks. One way this disease is spread is by feeding the meat from infected cattle to other cattle (meat from infected sheep may also cause the disease). This was a common practice on factory farms until the 1980s and 1990s when it was outlawed in most countries, due to its ability to cause BSE. At that time, thousands of cattle believed to have been exposed to BSE were killed to prevent further spread of the disease. Consuming beef from infected cattle causes a brain-wasting disease called new variant Creutzfeldt-Jakob disease (vCJD) in humans.