LOS ANGELES—Medina Spirit, the Kentucky Derby-winning horse that failed a drug test afterward and cast a cloud over the victory, died Dec. 6 during a workout at Santa Anita race track. “Following the completion of a routine morning workout, Medina Spirit collapsed on the track at Santa Anita Park and died suddenly of a probable cardiac event according to the on-site veterinary team who attended to him,” track officials said in a statement. “The Santa Anita Park veterinary team, led by Senior Veterinarian Dr. Laurie Bohannon, immediately took blood, hair and urine samples from Medina Spirit. Those samples were sent to the California Horse Racing Board. A full necropsy, as per protocol in California, run by the [University of California–Davis] School of Veterinary Medicine will be performed to try and ascertain the exact cause of this sudden death. The results of the necropsy and toxicology studies will be released by …