Wis. Stat. § 95.01: Administration of drugs to horses.

(1) No person may administer a drug to a horse, either internally or externally, for the purpose of altering the performance of the horse in a horse pulling contest.

(2) Persons in charge of a horse pulling contest may require as a condition of participation in the contest that the exhibitor submit the exhibitor’s horse for examination by a licensed veterinarian to determine the presence of drugs under sub. (1).