Skip to main content
Skip to main content

Executive Director’s message

Aspirin use in animals is illegal

Only US Food and Drug Administration (FDA)-approved drugs may be administered to animals. Aspirin (acetylsalicylic acid) is not FDA approved for use in animals or humans. Thus, it cannot be legally used to treat animals. Sodium salicylate is also not FDA approved and likewise cannot be used.

In early October 2024, the FDA published a Dear Veterinarian Letter (fda.gov/animal-veterinary/product-safety-information/dear-veterinarian-letter-regarding-use-aspirin-products-lactating-dairy-cattle) informing veterinarians that the use of aspirin products in dairy cattle was illegal because aspirin is not an FDA-approved drug. The FDA has confirmed that while this letter specifically addresses the use of aspirin in dairy cattle, the same use restriction applies to all animals including swine. Since this announcement, AASV staff have fielded several questions from AASV members asking about the extra-label use of these products under the Animal Medicinal Drug Use Clarification Act of 1994 (AMDUCA). Under AMDUCA, only the use of FDA-approved drugs is allowed, thus negating the use of aspirin and sodium salicylate in animals.

So, what is an FDA-approved drug? It is a drug that has gone through the FDA approval process meaning the drug is safe and effective when it is used according to the label. An FDA approval also ensures that the drug’s strength, quality, and purity are consistent from batch to batch, and that the drug’s labeling is truthful, complete, and not misleading. Any FDA-approved drug will have either a New Animal Drug Application (NADA) number, or for an approved generic animal drug, the Abbreviated New Animal Drug Application (ANADA) number. In most cases, FDA-approved brand name drugs will have the statement, “Approved by FDA under NADA # XXX-XXX” printed on the label. In the case of an FDA-approved generic animal drug, the statement, “Approved by FDA under ANADA # XXX-XXX” will appear on the label.

In 1996, the FDA issued a final rule implementing AMDUCA. This rule delineates the guidelines governing the extra-label use of animal and human drugs. It applies to both prescription and over-the-counter drugs. Prior to the enactment of AMDUCA, the use of any drug except in a manner specifically outlined on the label rendered the drug “unsafe” in the eyes of the law, making its use illegal.1

Under AMDUCA, extra-label drug treatment modalities are only allowed when the health of an animal is threatened or suffering or death may result from failure to treat. Extra-label drug use for production uses is prohibited. According to the FDA, the extra-label use of drugs for reproductive purposes would, in most cases, not be considered treatment and is thus not allowed under AMDUCA. Additionally, AMDUCA does not allow for extra-label use if an FDA-approved food-animal drug that contains the needed ingredient, in the proper dosage form, and is labeled for and effective against the condition being treated exists. Extra-label use of a drug is permitted if the existing labeled drug is clinically ineffective provided that the veterinarian has a basis for determining that the approved drug is ineffective in the animals being treated. Drug cost is not an acceptable reason for extra-label use. Preventive extra-label use is allowed if the veterinarian can substantiate that the health of the animals is threatened. However, AMDUCA does not allow for the extra-label use of any drugs administered through the feed. Extra-label administration of feed-grade antibiotics is illegal in all circumstances.2

Drugs may be used in an extra-label manner as prescribed under AMDUCA only if all the following conditions are met2:

  1. There is a valid veterinarian/client/patient relationship
    1. The veterinarian has assumed responsibility for making clinical judgments regarding the health of the animals 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 animals to initiate at least a general or preliminary diagnosis of the medical condition of the animals. This means that the veterinarian has recently seen and is personally acquainted with the keeping and care of the animals by virtue of an examination of the animals or by medically appropriate and timely visits to the premises where the animals 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.
  2. Use is permitted only by or under the supervision of a veterinarian. It is illegal for a layperson to use drugs in an extra-label manner without the approval of a veterinarian.
  3. Only FDA-approved animal and human drugs may be used in an extra-label manner.
  4. The AMDUCA applies only to dosage form drugs and drugs administered in the water. The Act does not allow for extra-label use through the feed.
  5. The veterinarian is responsible for establishing prolonged withdrawal times to ensure no violative residues or any residues which may cause public harm. Additional information on specific drugs may be found at farad.org.
  6. FDA may specifically disallow the use of certain drugs or classes of drugs. The following drugs are currently prohibited for use in food animals: chloramphenicol, clenbuterol, diethylstilbestrol, dimetridazole, ipronidazole, other nitroimidazoles, dipyrone, furazolidone, nitrofurazone, sulfonamide drugs in lactating dairy cattle (except approved use of sulfadimethoxine, sulfabromomethazine, and sulfaethoxypyridazine), fluoroquinolones, glycopeptides, phenylbutazone use in female dairy cattle 20 months of age or older, and cephalosporins (not including cephapirin) in cattle, swine, chickens, or turkeys for disease prevention purposes, at unapproved doses, frequencies, durations, or routes of administration, or if the drug is not approved for that species and production class.
  7. The AMDUCA only allows for the therapeutic extra-label use of drugs. Use for production reasons is not allowed. Drug cost is not a factor in determining extra-label drug use.
  8. Records must be maintained indicating the drug used (name and active ingredient), route of administration, dosage, number of animals treated, species treated, condition being treated, duration of treatment, and withdrawal time. These records must be kept for 2 years and are subject to FDA inspection.
  9. Drugs dispensed for extra-label use must be labeled individually and the label must contain the name and address of the prescribing veterinarian (or the name of the veterinarian and the name and address of the dispensing pharmacy), the established name of the drug, directions for use (including species; identification of the animal or herd, flock, pen, lot, or other group; dosage frequency; route of administration; and duration of therapy), any cautionary statements, and withdrawal time. The FDA states that case-labeling is appropriate when large numbers of animals need to be treated in an extra-label manner for a short period.

The AASV has designed a flow chart to aid veterinarians with decision-making regarding the appropriate use of drugs in an extra-label manner. This and other reference materials can be accessed under the “Vet Issues” tab on the AASV homepage (aasv.org/antimicrobial-use). In addition, veterinarians who have questions about AMDUCA or the extra-label use of drugs may contact FDA Center for Veterinary Medicine at AskCVM@fda.hhs.gov or 1-888-INFO-FDA (1-888-463-6332).

Harry Snelson, DVM
Executive Director

References

1. Waddell, John T. A practical look at AMDUCA and the risks for swine veterinarians. In: Proceedings of the AASV Annual Meeting. American Association of Swine Veterinarians; 2001:321-329.

2. Extralabel Drug Use in Animals. 21 CFR §530 (2024). https://www.ecfr.gov/current/title-21/chapter-I/subchapter-E/part-530