Correctly medicating animals is sometimes tricky. It requires a proper diagnosis and responsible veterinary treatment. Correctly medicating food-producing animals, such as cows, pigs, and chickens, is especially tricky. These animals provide us with food products like meat, milk, and eggs, and as the saying goes, “We are what we eat.”
When a food-producing animal is treated with a drug, residues of the drug may be present in or on food products made from that animal. FDA makes sure these drug residues pose little risk to people.
First, by looking at detailed information about the drug, FDA's toxicologists determine the “acceptable daily intake,” or “ADI.” The ADI is the largest amount of the drug that will not harm people even if they consume that amount every day.
Second, by using the ADI, residue chemists at FDA set the tolerance for the drug, which is the highest concentration of drug residues legally allowed to be in or on food products made from treated animals. During the approval process for a drug intended for use in food-producing animals, the drug company must provide FDA with appropriate and accurate testing methods for measuring residues in a specific edible tissue (for example, liver, kidney, tongue, or milk). These methods are used to test the tissue to make sure the drug residues aren’t above the legal tolerance. Eating food that contains even the highest legal concentration of residues (meaning, at the full tolerance) will not exceed the ADI and is safe for the consumer.
Finally, based on the tolerance, FDA's residue chemists set the withdrawal time. The withdrawal time is the time from when the animal was last treated with the drug to when the animal can be slaughtered for food or the animal’s milk or eggs can go to market. The withdrawal time allows for drug residues in the edible tissue of the treated animal to get to concentrations that are at or below the tolerance. If the withdrawal time is followed, food products made from a treated animal are safe to enter the food supply.
A drug that takes longer to be broken down or eliminated by the animal's body also takes longer to get down to concentrations that are at or below the tolerance in the meat, milk, or eggs. This results in a longer withdrawal time. Also, while there is only one tolerance for a given drug in a specific edible tissue (for example, cattle liver), the same drug may have different withdrawal times depending on how the drug is used, how it is given, or what type of food the treated animal produces. For example, the withdrawal time for a drug given to beef cattle (which provide us with meat) may be different than the withdrawal time for the same drug given to dairy cattle (which provide us with both meat and milk). Similarly, an injectable form of a drug may have a different withdrawal time than the same drug given in another form, such as orally in medicated feed.
Selling food products containing drug residues above the legal tolerance is illegal because such concentrations may harm people who eat that food. Giving either an over-the-counter or prescription animal drug to a food-producing animal can cause drug residues in the edible tissue of the treated animal to be above the legal tolerance. To avoid illegal residues and to keep food products safe, FDA reminds veterinarians and animal producers to follow the withdrawal time for every drug they use in food-producing animals. The agency also asks animal producers to “T.A.L.K. Before You Treat.”
T - Talk to your veterinarian. Always check with your veterinarian before giving any drug to your animals.
A - Ask if the drug is approved by FDA for use in your animals. FDA’s approval means the drug is safe and effective when it is used according to the label. FDA’s 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. If a drug is used in an extra-label manner in a food-producing animal, a veterinarian must be involved and is responsible for establishing an appropriate withdrawal time. Extra-label drug use means using an approved drug in a way that isn’t listed on the drug’s labeling. Extra-label drug use is sometimes called off-label because the use is “off the label.”
L - Look at the label. Know what drug you are giving and the dosage regimen. Be aware of the withdrawal time for the dosage regimen you are using. The dosage regimen includes:
- How much of the drug to give (the dose);
- How often to give it (the frequency);
- How long to give it (the duration); and
- How to give it (the route of administration). Various routes of administration include injecting the drug under the skin, into muscle, or into a vein; giving the drug by mouth; or applying the drug topically to the skin.
K - Keep complete treatment records. Good record-keeping will help you avoid illegal drug residues because you will know:
- Which animals were treated;
- What drug they were treated with;
- How they were treated (the dosage regimen used);
- Why they were treated; and
- When it is safe for food products made from treated animals to enter the food supply.
T - Talk to your veterinarian.
A - Ask if the drug is FDA-approved.
L - Look at the label.
K - Keep complete treatment records.