Veterinarians Allowed to Prescribe 'Extra-label' Drugs
Veterinary & Aquatic Services Department, Drs. Foster & Smith

'Extra-label drug use' describes the veterinary use of a drug in a manner for which it was not approved. Extra-label drug use occurs when a drug only approved for human use is used in animals, when a drug approved for one species of animal is used in another, or when a drug is used to treat a condition for which it was not approved. Examples of extra-label drug use in veterinary medicine include the use of phenobarbital (a drug only approved for use in humans) to treat epilepsy in dogs and cats; the use of ivermectin in dogs and cats (an antiparasitic only approved for use in cattle); and the use of enrofloxacin (Baytril) solution as a topical ear medication (only approved for use as an injectable).

Veterinarians have the ability to use drugs in an extra-label manner as a result of the Animal Medicinal Drug Use Clarification Act which became effective in December 1996. According to this act:

  • Extra-label drug use is permitted by veterinarians.
  • A veterinarian-client-patient relationship is prerequisite for all extra-label drug use.
  • An approved human drug may be used in an extra-label manner even when an identical, approved animal drug is available.
  • Veterinarians must keep records of any extra-label drug use for at least 2 years (in some states, longer).

Comments from our Veterinary Staff:

If veterinarians were not permitted to use drugs in an extra-label manner, our practice of medicine would be severely restricted since most drug companies do not market drugs specifically for animal purposes, e.g., insulin, many antibiotics, antifungals, antihistamines, etc. In addition, many drug companies which do market pharmaceuticals for animals may not test the product in multiple species and for multiple conditions.

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