Cal. Food & Agr. Code § 24008
A horse at an event is subject to examination under the direction of a licensed veterinarian of the department or agent of the licensed veterinarian. The appointed licensed veterinarian, with the approval of the department, may appoint technicians and agents to perform certain duties under this chapter that are not prohibited by other provisions of law. The examination may include physical, urine, or blood tests, or any other test or procedure at the discretion of the licensed veterinarian, that is necessary to effectuate the purposes of this chapter. Any or all horses in or from a class or all classes in an event or any horse entered into or from any class or competition or sale, whether in competition or not, if the horse is on the show or sale grounds, or any horse withdrawn by any person or trainer within 24 hours before a class for which it has been entered as well as any horse withdrawn from any horse sale, may be examined.
Ca. Food and Agric. Code § 24008