The steroid betamethasone was prohibited from use on race day.
Kentucky Derby winner Medina Spirit has tested positive for a banned race-day medication, its coach declared.
Bob Baffert, a Hall of Fame trainer, declared in a press conference at Churchill Downs Sunday the horse collapsed a post-race drug evaluation.
Medina Spirit was discovered to possess 21 picograms of this steroid betamethasone, which is double the legal limit in Kentucky racing, Baffert said.
On May 1, Medina Spirit won the Kentucky Derby with a half-length. Baffert's team learned of this favorable result from Kentucky officials on Saturday, he explained.
The evaluation results were obtained from the Kentucky Horse Racing Commission on Friday, Marc Guilfoil, executive director of the commission, said in a statement.
The win gave Baffert his seventh victory, a record for the race.
He described the test outcome as a"total injustice," stating Medina Spirit hadn't been treated with betamethasone, a joint injection/anti-inflammatory medicine, and that he didn't know the way the horse might have tested positive.
"I got the biggest gut-punch in rushing, for something I did not do," he said.
Medina Spirit has not been officially disqualified, but that may happen once more evaluations are complete, Baffert said.
In the findings of the analysis are upheld, Medina Spirit's Kentucky Derby win will be invalidated, as demonstrated by a statement from Churchill Downs.
"Failure to obey the rules and drug protocols jeopardizes the security of the horses and jockeys, the integrity of the game and the standing of the Kentucky Derby and all who participate," the announcement read. "Churchill Downs won't endure it"
Baffert vowed to be transparent through the analysis but added that his team will run their own evaluation.
"During the investigation, the owner and trainer of the horse is going to be given due process, and chance to appeal,"Guilfoil said in a statement, declining to comment further.
Baffert was suspended from the Arkansas Racing Commission for 15 days after two of the horses which won at Oaklawn Park tested positive for the painkiller lidocaine, The Associated Press reported.
He won an appeals case last month later testifying that the horses had been exposed to the drug inadvertently.