California Code, Food and Agricultural Code (Formerly Agricultural Code) - FAC § 14261

(a) Any livestock drug which is sold exclusively to, and used exclusively by, or under the direction of, a licensed veterinarian, nor to any livestock drug which is compounded by a registered pharmacist upon the prescription of a licensed veterinarian.

(b) Any drug or other preparation which is dispensed or compounded by a registered pharmacist at the request of the purchaser if such drug or preparation is sold at retail.

(c) Any commercial feed which is subject to Chapter 6 (commencing with Section 14901) of this division, irrespective of the presence in such commercial feed of any ingredients which otherwise would constitute a livestock drug.