No owner, trainer or any other person having the care, custody or control of a horse, whether entered in a race or not, whether the horse participated in the race or not, may refuse to produce a horse for testing, if requested by the Judges or Stewards during the race meeting. This refusal by the horse's owner, trainer or other person having care, custody or control, shall be deemed a violation of these rules and subject the licensee to a penalty. The horse entered in the race shall be scratched by the Judges or Stewards.
7 Pa. Code § 401.21