Cal. Food & Agr. Code § 24006
A trainer, owner, or both the trainer and owner, event manager, or any person who administers, attempts to administer, instructs, authorizes, aids, conspires with another to administer, or employs anyone who administers or attempts to administer a prohibited substance to a horse in violation of this chapter shall be subject to the penalties provided in this chapter that are applicable to the trainer or owner. The trainer and owner are both responsible for complying with this chapter after any course of medical therapy has been administered or prescribed by a licensed veterinarian employed by either the trainer or owner to examine and treat a horse. A licensed veterinarian who is employed by a trainer or owner to examine and treat a horse is not subject to the penalties provided in this chapter solely on account of that examination and treatment or prescription.
Ca. Food and Agric. Code § 24006