Medina Spirit, the controversial winner of the 2021 Kentucky Derby, died suddenly Monday after a workout at Santa Anita Park in California.

Amr Zedan, the owner of the thoroughbred, told Thoroughbred Daily News the horse suffered an apparent heart attack after workout. California Horse Racing Board equine medical director Jeff Blea told the website he saw a video of the workout and it appeared the colt had trouble breathing.

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John Velazquez atop Medina Spirit, center left, leads the pack out of the gates during the 146th Preakness Stakes horse race at Pimlico Race Course, Saturday, May 15, 2021, in Baltimore. (AP Photo/Julio Cortez)

Blea said by the time a veterinarian reached Medina Spirit, the horse had already died.

Santa Anita spokesman Mike Willman also confirmed the horse’s death.

The horse's trainer Bob Baffert added: "It is with great sadness that I am reporting Medina Spirit passed away today from a heart attack at Santa Anita following a workout. My entire barn is devastated by this news. Medina Spirit was a great champion, a member of our family who was loved by all, and we are deeply mourning his loss. I will always cherish the proud and personal memories of Medina Spirit and his tremendous spirit. Our most sincere condolences go out to Mr. Amr Zedan and the entire Zedan Racing Stables family. They are in our thoughts and prayers as we go through this difficult time."

Medina Spirit had won the Kentucky Derby in May but a failed drug test put the Derby win in question and led to the suspension of Baffert. The horse was found to have tested positive for 21 picograms of betamethasone, which is permitted unless it is found in the horse’s blood on race day.

Baffert explained on May 11 that 21 picograms of betamethasone in the post-race Derby sample may have come from a fungal ointment meant to treat dermatitis.

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Kentucky Derby winner Medina Spirit is walked to be groomed after a morning exercise at Pimlico Race Course ahead of the Preakness Stakes horse race, Tuesday, May 11, 2021, in Baltimore. (AP Photo/Julio Cortez)

Last week, Baffert’s lawyer Craig Robertson said a testing of a split urine sample was completed and showed that betamethasone in the horse’s system came from a topical ointment and not an injection.

"In other words, it has now been scientifically proven that what Bob Baffert said from the beginning was true – Medina Spirit was never injected with betamethasone and the findings following the Kentucky Derby were solely the result of the horse being treated for a skin condition by way of a topical ointment – all at the direction of Medina Spirit's veterinarian," Robertson said, via the Courier-Journal.

The California Horse Racing Board will implement a full necropsy.

Bob Baffert Medina Spirit

John Velazquez riding Medina Spirit crosses the finish line to win the 147th running of the Kentucky Derby at Churchill Downs in Louisville, Kentucky, on May 1, 2021.  (AP Photo/Jeff Roberson, File)

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Santa Anita Park came under fire in 2019 after dozens of horse deaths at the track. The park suspended racing for more than three weeks in March 2019. In 2020, about 15 horses died at the park.

The Associated Press contributed to this report.