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Conditions for Producers' Use of Livestock Drugs

Version 1.3 Written 4/21/99 Modified April 06, 2016

Warning: Due to new FDA regulations, parts of this webpage are out of date


This page is to provide access to information on the legal requirements for livestock producers to use drugs in food-producing animals to students enrolled in VMS 361 Agricultural Animal Health. I'm not a lawyer or a practitioner and this page is not intended to provide legal or clinical advice to producers or veterinarians. This document is not current on law specifics as the law changes when the FDA adapts to new scientific findings, changes in livestock husbandry, and market conditions.

Producer's use of livestock drugs:

Key Point:

Producers must use drugs according to the label on the container. Any usage contrary to the label by a producer is illegal under U.S. law. This label may be the manufacturer's label, which is approved by the FDA, or the label applied by the prescribing veterinarian.

Note that the FDA is responsible for the approval and licensing of livestock drugs and the USDA is responsible for the approval and licensing of livestock vaccines.

Drug labels must contain the following information:

Two Classes of drugs:

OTC ("over-the-counter") drugs:

These drugs are available to producers from many sources, such as feed stores. However, they can be used only according to the manufacturer's label unless directions for extra-label use are given on another label by a veterinarian within a valid veterinary-client-patient relationship.

The key to the classification of a drug as OTC rather than prescription is whether or not the manufacturer can develop instructions that an animal owner can understand and follow without serious consequences to the owner, the animal or the consumer of animal products.Under the law if such instructions can be written, they must be and the drug must be classified as an OTC drug.

Note:  As of December, 2016, the FDA requires veterinary oversight of all medically-important drug use in animals and bans the use of medically-important drugs in feed and water for anything other than animal health, specifically such as growth promotion. This includes a formal VCPR and individual prescriptions and means that veterinarians as well as producers will be held responsible for violations.

  • See Guidance for Industry #209: The judicious use of medically important antimicrobial drugs in food-producing animals - pdf
  • See Guidance for Industry #213: New Animal Drugs and New Animal Drug Combination Products administered in or on medicated feed or drinking water of food-producing animals: Recommendations for drug sponsors for voluntarily aligning product use conditions with GFI #209 - pdf

Prescription ("legend") drugs:

These drugs can only be purchased and used under the guidance of a licensed veterinarian in a valid VCPR (veterinary - client - patient relationship) with the producer. The producer can use these drugs only according to the label on the drug container, whether applied by the manufacturer or prescribing veterinarian.

By U.S. law, all such drugs have exactly the following legend on the container and the package insert:

Caution: Federal (US) law restricts this drug to use by or on the order of a licensed veterinarian.

Any other variation, such as "for sale to licensed veterinarians only", is for the company's marketing purposes only.

Veterinarian/Client/Patient Relationship (VCPR):

A valid VCPR exists when all of the three following conditions have been met:

  1. The veterinarian has assumed the responsibility for:

Making clinical judgments regarding the health of animals and the need for medical treatment

The client has agreed to follow the veterinarian's instructions

  1. The veterinarian has sufficient knowledge of the animals to initiate at least a preliminary diagnosis.

This means that the veterinarian must have recently seen and is personally acquainted with the keeping and care of the animals by either:

  • Exam of the animal(s)
  • Medically appropriate and timely visits to the premises of the animal.
  1. The veterinarian is readily available for follow-up evaluation or has arranged for emergency coverage in case of adverse reactions or failure of the treatment regimen.

FDA Animal Medicinal Use Clarification Act (AMDUCA)

For the veterinarian to use or to prescribe the use of any drug "off-label" or "extra-label" in food animals, the following criteria must be met:

Drugs that do not have a NADA or that are not approved human drugs cannot be used.

Drugs cannot be used off-label for purposes of production or reproduction

No approved drug labeled for such use or that contains the same drug in the dosage form and concentration exists

If an approved drug exists, the veterinarian must find within a valid VCPR that the approved drug is clinically ineffective for its intended use

If nothing in the literature enables the veterinarian to predict withdrawal times, then either that drug cannot be used or the animal cannot be used to produce food

On-line FDA AMDUCA Materials for further information:

Additional labeling required on the drug container:

Note that under any circumstance the producer can only use a drug according to its label, whether the label is applied by the manufacturer or by the prescribing veterinarian.

Drug use or extralabel use expressly prohibited in food animals:

AMDUCA prohibited drugs list - Code of Federal Regulations 21CFR530.41 (check for current list!):  

For examples of FDA's actions and penalties when these provisions are violated, see "Warning Letters", "Advisory Action Letters", or the FDA Veterinarian Newsletter

Interpretation Example: Hoards Dairyman article "Are Induced Lactation's Worth a Look?"  J. Stevenson Hoard's Dairyman Nov 788(1998).

The treatment described in the article includes estradiol, progesterone, dexamethazone, prolactin, and placental lactogen, none of which are approved by the FDA for this use.

Is this extra-label drug use legal for producers and veterinarians under AMDUCA?

Response from an FDA Center for Veterinary Medicine official:

"These compounds are new animal drugs as defined by the Federal Food, Drug, and Cosmetic Act (the Act), and must have pre-market approval by the Food and Drug Administration (FDA) for commercial marketing and use. These drug compounds are not labeled and approved by the FDA to initiate mammary growth and lactation."

"AMDUCA allows veterinarians to prescribe extra-label uses of approved animal drugs and approved human drugs for animals. AMDUCA provides that the extra-label use of approved animal drugs and human drugs must be in accordance with conditions established by the Secretary of Health and Human Services." - - - "The purpose of those regulations is to establish the conditions for extra-label use. 21CFR Part 530.2 clearly states that extra-label use is limited to treatment modalities when the health of an animal is threatened or suffering or death may result from failure to treat."

"AMDUCA does not extend extra-label use to production or reproduction uses. Initiating mammary growth and lactation are production claims. Use of these products in this manner, whether under a veterinarian's control or not, is not permitted under AMDUCA and would cause the drugs to be adulterated in violation of the Act."

Baytril 100 (fluoroquinolone) is an example of a special circumstance drug.

As Baytril 100 is a legend drug, it must be prescribed by a veterinarian in a valid VCPR. This drug is unusual in that the law expressly forbids any extra-label use under any circumstances by anyone. (21CFR530.41)


This product cannot be used in an extra-label manner by anyone!


The FDA Milk Safety Branch Pasteurized Milk Ordinance (PMO) places requirements on how drugs are stored and used on dairy farms producing Grade A milk. For example, drugs for lactating cows must be stored separately from drugs for non-lactating animals and clearly marked as different.

The 2007 Grade A Pasteurized Milk Ordinance (table of contents)

Additional On-line Information:

Changes to Antibiotics Regulations Coming December, 2016 (Dr. Mike Apley) - html

Regulations Today: Wading through VFDs, VCPRs, Prescriptions, ELDU Prohibitions, Proposed and Final Rules, and Guidance Documents (Dr. Mike Apley) - pdf

FDA Center for Veterinary Medicine

FARAD - Food Animal Residue Avoidance & Depletion Program

Residue avoidance:

AVMA on-line information for veterinary practitioners

Compendium of Veterinary Products - labels, package insert text

Counterfeit Drugs:

Counterfeit drugs are fakes that are visually indistinguishable from the actual product. Ten percent of the global drug supply is estimated to be counterfeit. Estimates as high as 40 percent counterfeits occur in some lesser developed countries including Mexico, and the proportion is increasing. Counterfeiting is the primary reason the FDA has resisted personal importation of drugs from outside US borders. Price provides the unscrupulous strong incentive to find ways of inserting counterfeits into the drug supply and distribution system.

Note: Thanks to Dr. Mike Apley, then of Iowa State Univ. and now of Kansas State Univ., for his comments on the first version of this page. Responsibility for any misinterpretations rests squarely with me.

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