A dairy cow from California tested positive for Mad Cow disease, or Bovine spongiform encephalopathy, setting off an investigation by the USDA.
The cow, which was 10 years old and could not stand, was sent to a facility that euthanizes sick or injured animals unfit for continued production or food supply. The animal was tested and found positive for an "atypical" form of the disease, thought to be caused by random mutation. Authorities claim there is no danger to the food supply, and there is no indication that any other animals from the faculty or the area were affected.
The mutation could be related to the type of food provided to the animal, but little is known about the factors that cause the disease. Only about .12% of cows in the US are tested for diseases, which stands in stark contrast to Japan and Europe, which test all cows over a certain age. The USDA prohibited a beef packer in Kansas from testing 100% of the animal in order to market the beef as mad cow-free, saying it would cause "instability in the market". Despite the public concern, mad cow is a rare condition, with only 4 reported cases ever in the US.
Learn more about issues of food safety at the World Animal Health Congress 2012!