Tetrahydrogestrinone, a new designer steroid that has rocked human athletics in recent months, has been duly placed on the radar of North American racing. But there are no plans to take action against the potential performance-enhancer, racing officials said."Frankly, I would be surprised if it was that prevalent on backstretches because its an anabolic steroid and there's lots of evidence that what they are used for in human athletes do not transfer to horses," said Dr. Scot Waterman, executive director of the national Racing Medication and Testing Consortium. "There are lots of reasons you don't want a muscle-bound horse. But that doesn't mean you don't keep an eye on these things."Both Waterman and Lonny Powell, president of the Association of Racing Commissioners International, said they have heard no anecdotal evidence of THG being used on horses since the drug was made public earlier this year. Some jurisdictions, such as Racing New South Wales, have already added THG testing to its screening process. However, Powell said there are no plans to do similar in North America."We do need to be acutely sensitive to things like this," Powell said. "Although it may not have any implications to the racing business, the fact so many performance-altering substances originate with Olympic athletes makes us extremely sensitive to these substances coming over to our industry."THG had been undetectable in tests in until an anonymous tipster revealed its presence to the U.S. Anti-Doping Agency. The Food and Drug Administration has since labeled THG as an unapproved drug."The interesting thing that came out of this story is the whole thing was started essentially by a good Samaritan that got a sample and sent it to a lab," Waterman said. "That is something as an industry we should be trying to do more of. You get plagued with these rumors but there is usually very little concrete evidence."