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U.S. Department of Health and Human Services

Animal & Veterinary

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FDA Veterinarian Newsletter September/October 2000 Volume XV, No. V

The American Veterinary Medical Association (AVMA) has developed principles on Judicious Therapeutic Use of Antimicrobials to help veterinarians make informed therapeutic decisions about these products. FDA's Center for Veterinary Medicine (CVM) contracted with AVMA to develop four species-specific brochures, a video, and a set of speeches to help promote these principles to veterinarians and veterinary students. The brochures are entitled, "Judicious Use of Antimicrobials for Poultry Veterinarians," "Judicious Use of Antimicrobials for Swine Veterinarians," "Judicious Use of Antimicrobials for Beef Cattle Veterinarians," and "Judicious Use of Antimicrobials for Dairy Cattle Veterinarians." CVM plans to make these brochures available this fall. Readers interested in obtaining copies may contact the FDA Veterinarian.

As the species-specific brochures state, "Whenever an animal or human host is exposed to antimicrobials, there will be some degree of selection for a resistant bacterial population. Selection will depend upon the type of antimicrobial used, the number of individuals treated, the dosage regimen, and the duration of treatment. Therefore, it is vital to limit therapeutic antimicrobial use in animals and humans to those situations where they are needed.

"The veterinary profession shares the concerns of the public, governmental agencies, and public health community regarding the broad issue of antimicrobial resistance and specifically the potential risk of resistance developing in animals with subsequent transfer to humans."

The brochures continue, "The overarching position of the AVMA is, 'When the decision is reached to use antimicrobials for therapy, veterinarians should strive to optimize therapeutic efficacy and minimize resistance to antimicrobials to protect public and animal health." The objectives of the AVMA are to:

  • support development of a scientific knowledge base that provides the basis for judicious therapeutic antimicrobial use,
  • support educational efforts that promote judicious therapeutic antimicrobial use,
  • preserve therapeutic efficacy of antimicrobials, and
  • ensure current and future availability of veterinary antimicrobials."

AVMA has developed fifteen general principles that emphasize preventive actions to avoid disease, other options before choosing to use antimicrobials, or the use of drugs, when possible, that are less important to human and animal needs. The principles are as follows:

  1. Preventive strategies, such as appropriate husbandry and hygiene, routine health monitoring, and immunizations, should be emphasized.
  2. Other therapeutic options should be considered prior to antimicrobial therapy.
  3. Judicious use of antimicrobials, when under the direction of a veterinarian, should meet all the requirements of a valid veterinarian-client-patient relationship.
  4. A veterinarian is required to direct the use of prescription antimicrobials or antimicrobials being used in an extralabel manner. This direction may take place only within the context of a valid veterinary-client-patient relationship (VCPR). A valid VCPR exists when all of the following conditions have been met:

    1. The veterinarian has assumed the responsibility for making clinical judgments regarding the health of the animal(s) and the need for medical treatment, and the client has agreed to follow the veterinarian’s instructions.
    2. The veterinarian has sufficient knowledge of the animal(s) to initiate at least a general or preliminary diagnosis of the medical condition of the animal(s). This means that the veterinarian has recently seen and is personally acquainted with the keeping and care of the animal(s) by virtue of an examination of the animal(s) or by medically appropriate and timely visits to the premises where the animal(s) are kept.
    3. The veterinarian is readily available for follow-up evaluation, or has arranged for emergency coverage, in the event of adverse reactions or failure of the treatment regimen.

      When it is not possible to make a direct clinical evaluation, the diagnosis should be based on past experience, on knowledge of the farm epidemiological status, and historical and/or on-going susceptibility testing.

  5. Prescription, Veterinary Feed Directive, and extra-label use of antimicrobials must meet all the requirements of a VCPR.
  6. Extralabel antimicrobial therapy must be prescribed only in accordance with the Animal Medicinal Drug Use Clarification Act amendments to the Food, Drug, and Cosmetic Act and its regulations (21 CFR Part 530).
  7. No drug can be marketed unless its quality, safety, and efficacy have been demonstrated. Therefore, the first line of choice should be based on the products approved for the species and the indication concerned. When no suitable product is approved for a specific condition or species, or the approved product is considered to be clinically ineffective, the choice of an alternative product should be based, whenever possible, on the results of valid scientific studies and a proven efficacy for the condition and species concerned.

    1. For food animals, extralabel drug use (ELDU) is not permitted if a drug exists that is labeled for the food animal species and contains the needed ingredient, is in the proper dosage form, is labeled for the indication, and is clinically effective.
    2. ELDU is permitted only by or under the supervision of a veterinarian.
    3. ELDU is allowed only for FDA approved animal and human drugs.
    4. ELDU is permitted for therapeutic purposes only when an animal’s health is suffering or threatened. ELDU is not permitted for production drugs (e.g., growth promotion).
    5. ELDU in feed is prohibited.
    6. ELDU is permitted for preventative purposes when an animal’s health is threatened.
    7. ELDU is not permitted if it results in a violative food residue, or any residue that may present a risk to public health.
    8. ELDU requires scientifically based drug withdrawal times to ensure food safety.
    9. The record and labeling requirements must be met.
    10. The FDA prohibits specific ELDU. For example, the following drugs are prohibited for extralabel use in food animals: chloramphenicol, clenbuterol, diethylstilbestrol, dimetridazole, ipronidazole, other nitroimidazoles, furazolidone (except for approved topical use), nitrofurazone (except for approved topical use), sulfonamide drugs in lactating dairy cows (except approved use of sulfadimethoxine, sulfabromomethazine, and sulfaethoxypyridazine), fluoroquinolones, and glycopeptides (example is vancomycin).
  8. Veterinarians should work with those responsible for the care of animals to use antimicrobials judiciously regardless of the distribution system through which the antimicrobial was obtained.
  9. Regimens for therapeutic antimicrobial use should be optimized using current pharmacological information and principles.
  10. Antimicrobials considered important in treating refractory infections in human or veterinary medicine should be used in animals only after careful review and reasonable justification. Consider using other antimicrobials for initial therapy.
  11. Use narrow spectrum antimicrobials whenever appropriate.
  12. Utilize culture and susceptibility results to aid in the selection of antimicrobials when clinically relevant.
  13. Therapeutic antimicrobial use should be confined to appropriate clinical indications. Inappropriate uses such as for uncomplicated viral infections should be avoided.
  14. Therapeutic exposure to antimicrobials should be minimized by treating only for as long as needed for the desired clinical response.
  15. Limit therapeutic antimicrobial treatment to ill or at risk animals, treating the fewest animals indicated
  16. Minimize environmental contamination with antimicrobials whenever possible.
  17. Accurate records of treatment and outcome should be used to evaluate therapeutic regimens.