Five of the six horses previously identified with equine herpesvirus-1 (EHV-1) at  Golden Gate Fields Thoroughbred Racetrack in California tested negative in samples taken Jan. 5, reported the director of the large animal clinic at the University of California, Davis.

“This strongly suggests that they are no longer shedding virus and therefore no longer contagious,” the director, David Wilson, DVM, said in an e-mail sent the morning of Jan. 6. He said re-sampling of the horses, all of which are segregated in the barn of trainer Lloyd Mason at the Albany, Calif., track, would be conducted Jan. 7.

The remaining horse to test positive was the last one to become infected, Wilson said.

“Our hope is that he will become negative next week,” Wilson said in the message. “We will retest him every couple of days so that we can find out as soon as possible when he becomes negative