A necropsy on 2021 Kentucky Derby winner Medina Spirit showed no definitive cause of death.

The California Horse Racing Board released the results of the examination done after the colt collapsed and died after a workout on Dec. 6 at Santa Anita.

Trainer Bob Baffert said the colt suffered a heart attack.

The report said Medina Spirit’s swollen lungs and foam in his windpipe, as well as enlarged spleen “are common in horses dying suddenly, and are compatible with, but not specific for a cardiac cause of death.”

Last year’s Derby win was quickly mired in controversy after the revelation that Medina Spirit failed a post-race drug test. That led Churchill Downs to suspend Baffert for two years.

Amina Elahi contributed to this story.