Medina Spirit is only the third horse in the race’s 147-year history to receive such a penalty after finishing first. The decision means the colt’s owner will not collect the $1.8 million first-place check, which was never paid out and will now go to Mandaloun’s owner.

Churchill Downs, the track in Louisville, Ky., that hosts the Derby, said in a statement that it now recognizes Mandaloun as the winner of the 2021 race.

The ruling also erased the Hall of Fame trainer Bob Baffert’s seventh Kentucky Derby victory, which had been a record.

In addition, Baffert was suspended for 90 days beginning March 8 and fined $7,500.

The drug found in Medina Spirit’s system was betamethasone, a corticosteroid injected into joints to reduce pain and swelling. Baffert said the drug was applied topically to treat a skin rash on Medina Spirit’s hind end.

The disqualification puts a new stain on a sport that has been troubled by doping problems and places Baffert’s reputation and future in the sport in jeopardy. Baffert, whose horses won the Triple Crown in 2015 and 2018, is thoroughbred horse racing’s most recognizable personality.

The decision by Kentucky racing officials comes at a time when the Triple Crown season is heating up and the quest for qualifying points to earn a spot in the Derby’s starting gate is getting urgent. Churchill Downs had already suspended Baffert from the race for two years and refused to award qualifying points to horses he would train for the 2022 Derby.

Baffert has three accomplished 3-year-old colts in his barn — two of them, Corniche and Newgrange, are undefeated. If their owners want to participate in the Derby, they must transfer their horses to another trainer and hope to earn qualifying points in future prep races.

Last month, Baffert threatened to sue Churchill Downs if the track did not lift the two-year ban, saying that his right to due process was violated and that he had been unlawfully excluded from Churchill Downs and the Derby.

Bill Carstanjen, the chief executive of Churchill Downs, said the complaint was “meritless.” He threatened to countersue if it was filed and emphasized that Baffert was a repeat offender. In all, Baffert’s horses have failed 30 drug tests over four decades, including five in a recent 13-month period.

The necropsy results for Medina Spirit, who died in December indicated that the colt most likely died of a heart attack. The disqualification, along with recent guilty pleas and convictions of prominent trainers and veterinarians for doping horses, lends urgency to the implementation of the Horseracing Integrity and Safety Act.

Set to take effect July 1, 2022, it calls for a board overseen by the Federal Trade Commission to write rules and penalties to be enforced by the United States Anti-Doping Agency, which regulates Olympic and other elite athletes in the United States.

Baffert and Medina Spirit join Maximum Security and Dancer’s Image as the only horses to have their Derby victories overturned.

In 2019, Maximum Security was first across the finish line, only to be disqualified for almost knocking over a rival horse in the far turn and slowing the momentum of others. The next year, Maximum Security’s trainer, Jason Servis, was among 27 people charged by federal prosecutors in a wide-ranging scheme to secretly dope horses and cheat the betting public. He is awaiting trial.

In 1968, Dancer’s Image’s victory was taken away after a drug test showed the presence of a banned anti-inflammatory drug. That case lingered in the courts for four years before the disqualification was finally upheld.