California Code, Revenue and Taxation Code - RTC § 6018.1

A licensed veterinarian is a consumer of, and shall not be considered a retailer within the provisions of this part with respect to, drugs and medicines used or furnished by him or her in the performance of his or her professional services.

For the purposes of this section, “drugs and medicines” includes substances or preparations intended for use in the diagnosis, cure, mitigation, treatment, or prevention of disease in animals and which is commonly recognized as a substance or preparation intended for this use. The term includes legend drugs, pills and capsules (other than vitamins), liquid medications, injected drugs, ointments, vaccines, intravenous fluids, and medicated soaps if those soaps are available only to veterinarians. The term does not include vitamins, shampoos, pet foods, prescription diet foods, artificial diets, flea powders, and flea sprays.