A second post-race drug test for Kentucky Derby winner Medina Spirit confirmed a prohibited substance was present, a lawyer for the horse"s trainer said on Wednesday, raising the possibility the dark bay colt might be disqualified. The lawyer for Hall of Fame trainer Bob Baffert, who won a record seventh Kentucky Derby with Medina Spirit on May 1, said a second sample found the anti-inflammatory drug betamethasone at a prohibited level. Baffert has previously said Otomax, an anti-fungal ointment to treat dermatitis, could be the source of Medina Spirit"s positive test and the trainer"s lawyer said further testing is being conducted. "There is other testing that is being conducted, including DNA testing. We expect this additional testing to confirm that the presence of the betamethasone was from the topical ointment, Otomax, and not an injection," attorney Craig Robertson told Reuters in an email. "At the end of the day, we anticipate this case to be about the treatment of Medina Spirit"s skin rash with Otomax." Baffert, who won a record seventh Kentucky Derby with Medina Spirit, previously said the horse developed dermatitis on his hind end in April and his veterinarian recommended daily use of Otomax to prevent it from spreading. Medina Spirit"s initial sample after the Kentucky Derby at Churchill Downs showed 21 picograms of betamethasone, over the legal limit in Kentucky racing, and Robertson said the second test confirmed findings of the substance at 25 picograms. Churchill Downs told Reuters in an email it is awaiting official notification of the split sample test results from the Kentucky Horse Racing Commission. The racetrack has previously said that if a second round of testing showed the presence of betamethasone, Medina Spirit would be disqualified and runner-up Mandaloun would be declared the winner. read more Despite the original positive test, Medina Spirit was cleared to run in the May 15 Preakness Stakes, the second jewel in U.S. thoroughbred racing"s Triple Crown, where he finished third behind Rombauer.