In June 2005, the USDA received final confirmation from the Veterinary Laboratories Agency (VLA) in Weybridge, U.K., that a sample taken from an animal blocked from entering the food supply in November 2004, had indeed tested positive for bovine spongiform encephalopathy (BSE).

DNA testing proved that the 12 year old cow had been born and raised on a ranch in Texas for its entire life, making this the first homegrown BSE case in the U.S.

As a non-ambulatory or "downer" cow, considered a higher risk, the animal was blocked from entering the human food supply and selected for BSE testing. After initial screening tests conducted by the USDA proved inconclusive, and further testing revealed conflicting results, USDA officials were prompted to send the sample to the VLA - the European Comission TSE reference laboratory.

Over six months after the first tests were run, Weybridge officials confirmed the sample as testing positive for BSE, using a Western blot test. The Western blot technique is known to give a very reliable diagnosis even in old samples.