The U.S. Department of Agriculture says a possible third case of mad cow disease has been discovered by British and American labs.

USDA Chief Veterinarian John Clifford says, "The suspect animal, which was destroyed after having trouble giving birth in April, produced an inconclusive result in an initial round of testing for the brain-wasting disease."

The USDA is conducting further tests at the National Veterinary Services Laboratories in Ames, Iowa and consultating with experts from the international reference laboratory in Weybridge, England.

"We are also sending samples from this animal to the Weybridge laboratory for further testing," Clifford says.

The first case of mad cow disease in the U.S. was discovered in 2003, while the second was discovered just last month on a Texas ranch.