Mad Cow Disease and Horses

Bovine spongiform encephalopathy (BSE) was first identified in the United Kingdom in 1986. A fact sheet from Iowa State University said BSE is one of several diseases called transmissible spongiform encephalopathies (TSE). There are three rare forms of TSE diseases in humans, scrapie in sheep (not transmissible to man), chronic wasting disease in deer and elk (not transmissible to man), and mink encephalopathy (not transmissible to man). There are no known TSE in swine, poultry, or horses.

All of the TSE diseases are caused by the development of an aberrant protein called a prion in the central nervous system. These build up and lead to neurologic disease. They contain no DNA, so are not considered "living." The precise mechanism of invasion of the body, replication, and transmission are not known.

Bioassays have identified the presence of the BSE agent in the brain, spinal cord, retina, dorsal root ganglia (nervous tissue located near the backbone), distal ileum, and the bone marrow of cattle experimentally infected with this agent by the oral route. The scientific community believes that there is no evidence to demonstrate that muscle cuts or whole muscle meats that come from animals infected with BSE are at risk of harboring the causative agent of the disease. Milk products are also considered to be safe.

In fact, it is the use of the brain/spinal cord by-products in animal feeds that is thought to be the leading cause of spread of BSE.

While horses are not infected by BSE, horse owners should become educated about BSE. For more information, visit the U.S. Department of Agriculture's web site at

About the Author

Kimberly S. Brown

Kimberly S. Brown was the Publisher/Editor of The Horse: Your Guide To Equine Health Care from June 2008 to March 2010, and she served in various positions at Blood-Horse Publications since 1980.

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