Mo. Rev. Stat. § 313.700: Drugs or medications, unauthorized use prohibited, penalty.

No drug or medication shall be administered to any horse entered for competition in any horse race unless that specific drug or medication has been individually approved by the commission for use at times permitted by rule or rules promulgated by the commission. Any individual found guilty of administering a foreign substance to a horse entered to race, with the intent to affect the result of the race in which the horse is entered, shall be guilty of a class B felony.