(CNN) Kentucky Derby winner Medina Spirit has tested positive for elevated levels of betamethasone, trainer Bob Baffert revealed Sunday, throwing the horse's victory last weekend at Churchill Downs into question.
Speaking to reporters Sunday morning, Baffert denied that the horse had ever been treated with the drug, which is sometimes used for joint pain in horses, saying his team would conduct its own investigation.
"Yesterday I got the biggest gut punch in racing for something that I didn't do," Baffert said, adding it was an "injustice to the horse."
"I don't feel embarrassed, I feel like I was wronged. But I'm going to fight it."
Betamethasone is an anti-inflammatory corticosteroid that is allowed in horse racing at a certain level. But Baffert said he'd been informed that Medina Spirit's postrace test detected 21 picograms per milliliter -- more than double the legal threshold in Kentucky racing.
Churchill Downs on Sunday announced it would immediately suspend Baffert, barring him from entering horses to race at the track.
"Failure to comply with the rules and medication protocols jeopardizes the safety of the horses and jockeys, the integrity of our sport and the reputation of the Kentucky Derby and all who participate," the Churchill Downs' statement said.
The news comes just over a week after Medina Spirit, the 3-year-old brown colt won the Derby, at Churchill Downs in Louisville, Kentucky, beating out second-place Mandaloun by half a length. It was a record seventh victory for Baffert at the Derby, one of the sport's most famous events.
As of Sunday, Medina Spirit had not been disqualified, Baffert said. A split sample from Medina Spirit will now be tested, and if the original results are confirmed, then Baffert would have a chance to appeal.
If an appeal is unsuccessful, Medina Spirit would be stripped of the Kentucky Derby crown as well as the winning prize money. The last winning horse to be disqualified from the Kentucky Derby after failing a drug test was Dancer's Image in 1968.
"To be clear, if the findings are upheld, Medina Spirit's results in the Kentucky Derby will be invalidated and Mandaloun will be declared the winner," Churchill Downs' statement Sunday said.
"We will await the conclusion of the Kentucky Horse Racing Commissions' investigation before taking further steps."
The commission confirmed it was investigating the test findings in a statement Sunday. The test was conducted May 1, the day of the race, and the results were obtained May 7.
"During the investigation, both the trainer and owner of the horse will be afforded due process, and opportunity to appeal," the commission said. "Therefore, the KHRC will not provide further comment at this time."
This is not Baffert's first run-in with reports that his horse failed a drug test: Last month, according to multiple reports, including the Arkansas Democrat-Gazette, the Arkansas Racing Commission upheld a ruling that two of Baffert's horses had tested positive for lidocaine beyond the accepted levels. However, the commission dropped a 15-day suspension for Baffert.
Baffert alluded to previous controversies on Sunday -- "I don't feel safe to train," he said -- but cast the allegation about Medina Spirit as an issue with the broader horse racing industry, saying the industry "needs to step up and we need to do a better job in racing."
"I'm not a conspiracy (theorist) -- I know everybody's not out to get me. But there's definitely something wrong. Why is it happening, you know, to me?" he asked. "There's problems in racing, but it's not Bob Baffert."
The organizers of the Preakness Stakes -- the second jewel of horse racing's Triple Crown -- said they would review the "relevant facts and information" related to Medina Spirit's test before making a decision on the horse's entry to the race in Baltimore next Saturday.
"We are consulting with the Maryland Racing Commission and any decision regarding the entry of Medina Spirit in the 146th Preakness Stakes will be made after review of the facts," the statement said.
In 2009, Baffert was inducted into the sport's Hall of Fame, which puts his number of wins at 3,120, with more than $320 million in purse earnings.
He became the 11th trainer to win the Triple Crown in 2015 when American Pharoah won the Kentucky Derby, the Preakness Stakes and the Belmont Stakes. He became only the second trainer to ever win the Triple Crown twice just a few years later with the horse Justify.