What is Mad Cow Disease?
Bovine spongiform encephalopathy (BSE), also known as Mad Cow Disease, is a chronic, fatal disease that affects the central nervous system of cattle. Caused by the formation of abnormally shaped proteins called prions, BSE had not been found in the US until a cow imported from Canada tested positive for the brain-wasting illness in Washington State in December 2003. The disease's incubation period is long, ranging from 3 to 6 years. First diagnosed in the United Kingdom in 1986, the disease reached its peak in that country in 1992.

How Do Cattle Contract BSE?
Experts generally agree that BSE is spread when cattle are fed meat and bone meal that contains brain or spinal cord from an infected animal. In 1997, the FDA banned cattle feed from containing ruminant meat and bone meal. Farmers used to feed such meal to their cattle because it was an inexpensive source of protein and minerals and it improved animal production. The USDA is trying to determine whether the Washington cow ate infected feed while in Canada. Scientists believe it is unlikely that cow-to-calf transmission occurs. If maternal transmission does occur, it would occur late in the incubation period and the mother most likely would show clinical signs.

Does the Disease Pose a Risk to Humans?
Humans may contract variant Creutzfeldt-Jakob disease if they consume tissues from cattle which contain the disease-causing prions, specifically the brain or spinal cord. There is no cure for this disease, which was responsible for about 150 human deaths in Europe. Is the Food Supply Safe? While the discovery of BSE in the US has increased public concern about the safety of meat, the USDA has stated that the food supply is safe and has recalled all beef related to this case as a precaution. Milk and dairy products are considered universally safe; the transmission of BSE or its disease-causing prions through these products has never been demonstrated.

How is the Public Being Protected From Mad Cow Disease?

• In addition to tracking the location, feed history and offspring of the positive cow and its Canadian herd (at press time, one cow from the herd had been located on a dairy farm in Oregon), the USDA has put additional safeguards into place:
• The USDA is in the process of implementing a national identification system to track animals more efficiently in the event of a disease outbreak.
  Downer cattle are no longer allowed to be processed for human food. Previously, they were allowed into the food chain if they were not sick. Of the 35 million cattle slaughtered each year, about 200,000 are downers, including the positive cow from Washington State. ¦
• Beef from animals tested for BSE under the USDA program must be held from the food supply until the test confirms a negative result. ¦
• Mechanically separated meat is no longer allowed into the food chain and meat obtained through an industrial process called advanced meat recovery may no longer include the dorsal root ganglia, a cluster of cells along the spine, in addition to the previously excluded brain and spinal tissue.

Is My Pet At Risk?
While approximately 60 cats in Britain have contracted the related illness feline spongiform encephalopathy (FSE), the risk to your cat is considered to be extremely low. Due to a wide variety of feeding methods (table scraps to pet foods), it is not known how the cats contracted FSE. Dogs are not known to contract this disease.

The Oregon Veterinary Medical Association is a nonprofit organization of veterinarians

Oregon Veterinary Medical Association www.oregonvma.org © 2005 Oregon Veterinary Medical Association