In recent months, the Food and Drug Administration has sent warning letters to several food supply veterinarians for illegal extralabel drug use.

In one instance, a veterinarian prescribed an extralabel use of flunixin, which caused an illegal residue in two dairy cows sold for human consumption. Flunixin is not approved for intramuscular administration in nonlactating dairy cows. The veterinarian was also chastised for the more egregious error of using a blanket prescription form that allowed a producer unlimited access to prescription drugs for indiscriminate extralabel use.

In another instance, two veterinarians used sulfadimethoxine 12.5 percent oral solution in an extralabel manner by administering the drug intravenously to lactating dairy cattle. The extralabel use of sulfonamide drugs, including sulfadimethoxine, in lactating dairy cattle is prohibited. The veterinarians were also warned about prescribing and/or administering 100 mg/mL oxytetracycline HCl injection in an extralabel manner to treat lactating dairy cattle without following proper procedure.

Prior to prescribing or dispensing an approved animal drug for an extralabel use in food animals, the veterinarian must make a careful diagnosis and evaluation of the condition for which the drug is to be used; establish a substantially extended withdrawal period, supported by appropriate scientific information, prior to marketing an edible product; institute procedures to ensure that the identity of the treated animal or animals is carefully maintained; and take appropriate measures to ensure that assigned time frames for withdrawal are met. The latter includes specifying a withdrawal/discard time on a drug label for any food that might be derived from a treated animal.

To obtain scientific information to determine withdrawal intervals, contact the Food Animal Residue Avoidance Databank at (888) USFARAD.

For a copy of the "FDA and the Veterinarian" booklet and AVMA's extralabel drug use brochure, free of charge, e-mail jdabetic@avma.org or call (800) 248-2862, Ext. 6636.