The extra-label use of any veterinary drug in or on a food-producing animal by any person other than a veterinarian or a person working under the control of a veterinarian is a prohibited act. Extra-label use of these drugs by or on the order of a veterinarian is not prohibited provided all the following conditions are met:

(1)  A careful medical diagnosis is made by the veterinarian within the context of a valid veterinarian-client/patient relationship.

(2)  A determination is made by the veterinarian that there is no marketed drug specifically labeled to treat the condition diagnosed, or that drug therapy as recommended by the labeling has been found clinically ineffective in the animal(s) to be treated.

(3)  Procedures are instituted to assure that the identity of the treated animal is carefully maintained.

(4)  A significantly extended time period is assigned for drug withdrawal prior to marketing meat, milk, or eggs; steps are taken to assure that the recommended withdrawal times are met; and no illegal residues occur as determined by the U.S. FDA or other federal agency which may have jurisdiction, e.g. USDA, EPA.