The Kentucky Horse Racing Commission (KHRC) said July 11 that no dermorphin, a pain-killer more powerful than morphine, was found in samples tested from some horses that raced in this year’s Kentucky Derby Presented by Yum! Brands (gr. I) and Kentucky Oaks (gr. I).

The testing was performed by HFL Sports Science Laboratory in Lexington.

As reported previously, Mary Scollay, DVM, equine medical director for the KHRC, said the lab began testing for dermorphin in late June after more than 30 racehorses tested positive for the drug in recent weeks. That process included retrospective testing of samples taken from this year’s Derby and Oaks entrants.

Dermorphin, a fluid obtained from certain South American frogs, is a hepta-peptide that is a natural opiate more potent than morphine but less likely to produce addiction; it can kill pain, stimulate running, and suppress the feeling of exhaustion after exercise, according to the National Horsemen’s Benevolent and Protective Association (NHBPA). The NHBPA said the organization has "zero tolerance" for trainers who use illegal Class 1 and 2 substances. Dermorphin is a Class 1 drug under the classification of the Association of Racing Commissioners International