Medina Spirit, who finished first in this year's Kentucky Derby, died suddenly after working at Santa Anita on Monday.

The three-year-old beat Mandaloun by half a length in the Churchill Downs Classic back in May, but his victory remains up in the air after Bob Baffert’s charge tested positive for the anti-inflammatory drug betamethasone after the race, with the substance said to have been in a topical ointment used to treat a skin issue.

Medina Spirit went on to finish third in the Preakness, win a Listed heat at Del Mar and the Grade One Awesome Again Stakes at Santa Anita before chasing home Knicks Go in last month’s Breeders’ Cup Classic in what transpired to be his final race.

The son of Protonico is reported to have collapsed after breezing over five furlongs at the California track.

Owner Amr Zedan told Thoroughbred Daily News: "I just heard. He had a heart attack. It was quick and he didn’t suffer. It’s unfortunate.

"In a moment like this there is not much that we can do. All I can say is that he gave us the ride of our lives and brought everyone together.

"We are mourning this loss, Bob, myself, our team and Johnny (Velazquez, jockey), as well. We are all very sad.

"We had such high hopes for him and so many plans. We were going to go to the Saudi Cup and possibly to Dubai. We wanted to campaign him all next year.

"The last thing I expected was to hear something like this. It is God’s will."