Test samples taken from some runners in this year’s Kentucky Derby Presented by Yum! Brands (gr. I) and Kentucky Oaks (gr. I) are among those now being tested for dermorphin, a powerful painkiller detected in more than 30 racehorses in recent weeks.

According to Mary Scollay, DVM, equine medical director for the Kentucky Horse Racing Commission, the state’s equine laboratory began testing for dermorphin last week. That process includes retrospective testing of samples taken from this year’s Derby and Oaks entrants.

In Kentucky, a minimum of three post-race samples from graded stakes races are tested, with the stewards typically selecting one more horse for testing, for a total of four per race, according to Scollay. She said there were five samples taken among the 20 horses that ran in the Derby and four from the Oaks.

Under Kentucky regulations, all post-race samples are retained for six months. A subset of those samples is then retained for an extended period and the state is able to test the retained samples as "emerging threats are identified and corresponding testing becomes available," Scollay said in an e-mail response to an inquiry about Kentucky’s testing protocol for dermorphin