LEXINGTON, Ky.– Scot Waterman, the executive director of the industry-funded Racing Medication and Testing Consortium since its formation in 2003, has submitted his resignation, effective at the end of April, according to two officials who work closely with the organization.The resignation introduces doubts about whether the RMTC will remain in operation, according to the officials. Waterman, who oversees a small staff, has been the driving force behind the organization, which receives the brunt of its funding from horsemen’s groups and other industry sources.The RMTC was formed to develop policies on medication rules and regulations that are backed up by scientific research, particularly in the area of setting so-called threshold levels for the amount of a drug that can be present in a horse’s post-race blood and urine samples without being considered a positive. Its work has met with resistance from a number of industry participants, and its call last year for regulatory bodies to reduce the threshold level for the popular painkiller phenylbutazone was a particular source of irritation to many horsemen.Waterman did not return phone calls on Thursday.The two officials who said that Waterman had submitted his resignation spoke on the condition of anonymity, citing Waterman’s reluctance to discuss his decision publicly. However, both said that he had become frustrated with the push-back to the consortium’s work.“It’s been a constant battle for him,” one official said. “He just got tired of trying to change the tone. He did great work, but this industry has a way of eating its own. Scot just doesn’t have the disposition for that.”A small-animal veterinarian prior to being brought on at the RMTC, Waterman is a also graduate of the University of Arizona’s Race Track Industry Program and has owned Thoroughbreds. He is based in Lexington, but has a home in Tucson, Ariz.Waterman had recently worked with the state of West Virginia to update its medication rules. The rules were adopted earlier this week. Both officials said that Waterman had made his decision prior to a recent call by officials at the Association of Racing Commissioners International to eliminate raceday medication within the next five years. That call has since been endorsed by a handful of organizations, including the Jockey Club and the Kentucky Thoroughbred Association, which represents owners and breeders in the state. However, national and local horsemen’s groups have indicated that they will continue to resist any effort to rollback the legal raceday use of the diuretic furosemide, which is used to treat bleeding in the lungs.According to the officials, Waterman has said that he plans to return to Tucson to open a small-animal veterinary practice.