Link found to amphetamine positives

The Canadian Pari-Mutuel Agency has issued a warning to trainers and veterinarians that the de-worming drug and immune-system stimulant levamisole may be linked to a rash of mysterious positives for the amphetamine aminorex.

The agency administered the levamisole to a number of horses and then tested the horses' urine samples for traces of aminorex. The agency is also testing other drugs to see if any links to aminorex are found.

In the past two years, more than two dozen horses, mostly Standardbreds, have tested positive for aminorex, a methamphetamine that has not been manufactured for more than 20 years. The positives have baffled regulators in Ohio, Pennsylvania, and Canada, where they have been concentrated.

Although Pennsylvania handed out suspensions to two trainers in 2005, the state has stayed the penalties for 17 other positives that have been found as recently as late last year.

Ben Noldt, the chairman of the Pennsylvania State Racing Commission, did not return a phone call on Thursday, and it was unclear how the Canadian agency's findings would impact those cases.

Dr. Scot Waterman, the executive director of the Racing Medication and Testing Consortium, said that the test results were "interesting," but he doubted whether the findings explained all the aminorex positives.

"I think we're in the third or fourth inning on this," Waterman said. "There's probably still a lot more to be learned."