A post-race blood sample from the Kentucky Derby tested positive for 21 picograms of the steroid betamethasone. Betamethasone is legal for use as a therapeutic drug in horses, but as a steroid, its use is legally limited when competing in racing. 21 picograms (21 one-trillionths of a gram) is more than double the legal limit in Kentucky horse racing - 10 picograms. It is also prohibited from being administered any fewer than 14 days prior to a race. Trainer Bob Baffert, who won his record-set