Medina Spirit, the horse at the centre of a doping controversy at this year’s Kentucky Derby, has died during a workout. The colt suffered a suspected heart attack while working out at California’s Santa Anita track on Monday. “Near the end of his breeze this morning, he did not feel right and his rider tried to pull him up,” Jeff Blea, the equine medical director for the California Horse Racing Board, told the New York Times. “He went down. Our vet on the scene got there immediately and he was already expired.” Medina Spirit was a central character in one of US racing’s biggest controversies in decades. He crossed the line first in May’s race but failed a post-race drugs test. His trainer, Bob Baffert, was banned from entering horses at the Kentucky Derby for two years after the controversy. He denied deliberately doping the horse, which had been a 12-1 outsider to win the race, and blamed the failed test on an ointment used to treat a rash on Medina Spirit. Medina Spirit had enjoyed recent success, finishing second in the Breeders’ Cup Classic in November. Baffert has yet to comment on the death. An attorney for the horse’s owner, Amr Zedan, told the New York Times his client and Baffert were “wracked with grief” over the death.