EXPLAINER: Derby winner's failed test latest in horse doping

Kentucky Derby winner Medina Spirit's failed postrace drug test has put doping horses back in the spotlight when the sport would rather have the focus on the Triple Crown. Medina Spirit tested positive for the steroid betamethasone. It's allowed in Kentucky as a therapeutic up to 14 days before a horse races. Trainer Bob Baffert says 21 picograms of the substance was found in Medina Spirit's system. Even a trace amount of the steroid detected on race day is a violation. Baffert and the colt's owners have requested a second round of testing. If the violation is upheld, Medina Spirit would be disqualified and Mandaloun named winner of the Kentucky Derby.