by Sally Colby
“The FDA is responsible for the regulation of all human and animal drugs in this country,” said Dr. Troy Brick, assistant professor in preventive medicine at the Ohio State University. “Their primary responsibility is to the public. They need to make sure that the food supply is safe, and they feel that in some instances, the use of antibiotics in our animals is contributing to resistance in some bacteria. I would argue that I do not believe that the literature agrees with that — there are arguments on both sides.”
There’s been a lot of talk recently about new regulations regarding antibiotics for livestock use. The FDA is currently in the process of reviewing and reworking the new regulation, but some aspects of drug use in livestock will always remain the same.
Like others, Brick doesn’t believe agriculture is solely responsible for the growing issue of antibiotic resistance. He provided several examples of key antibiotics that cattlemen rely on for treating disease, and noted that ceftiofur, a third generation cephalosporin (Naxel®, Excede®) is one of the most powerful and widely used antibiotics used in the U.S. cattle industry.
Brick cited an article that noted in a random test, an animal tested positive for ceftiofur at 5.61 mg/kg, which is 14 times higher than the 0.04 mg/kg tolerance set by the FDA. Unfortunately, the cattleman didn’t help the cause because he talked about how salvaging the cow was his main concern. The attitude of ‘we’re going to send her to the stock yard so we can get something out of her no matter what’ hasn’t helped producers who use drugs within legal guidelines.
“All drugs have a label that explains their lawful use,” said Brick. “Until 1996, it was absolutely illegal for anyone to use a drug in any other manner than what it explicitly stated on the label. In 1996, the Animal Medicinal Drug Use Clarification Act (AMDUCA) was passed, and that allowed veterinarians to use some of the drugs in an extra-label manner.”
The letters ELDU stands for extra-label drug use, which means a veterinarian can prescribe that drug when the health and well-being of an animal or group of animals is at stake, as long as certain conditions are met. “That means if you, as a producer, are using a drug in any means other than what is written on the label, you are using it illegally,” said Brick. “Extra-label drug use is allowed for FDA-approved human and animal drugs. It isn’t allowed for drugs that are brought into the country mass quantities and re-bottled without FDA approval.”
In order for a veterinarian to prescribe drugs to be used in an extra-label manner, the veterinarian must have to have a valid client/patient relationship, or VCPR, with the producer. In the past, a valid VCPR could be established through a veterinarian’s visit to the farm, or the result of a producer asking a veterinarian for advice; as long as the veterinarian was familiar with that farm’s production methods and the health concerns on the farm. Brick says many states and state veterinary medical associations are now recommending veterinarians use a written VCPR that details the agreement and is signed by the producer and the veterinarian.
Brick says extra-label drugs can be used only for therapeutic purposes, which means the animal is suffering or its health is threatened. Extra-label drug use cannot be for production purposes. “One thing that is explicit in the rules for extra-label drug use is that cost is not a valid reason,” he said. “So if I can buy a bottle penicillin for humans for $10 or a veterinary bottle of penicillin for $50, I have to buy the veterinary bottle and use that because it’s labeled for animals and the human bottle is not.”
Extra-label drug use is not permitted if it results in a violative food residue or any residue that may present a risk to public health. “That means that if the vet prescribes a drug that is extra-label or prescribes a larger dose than what is on the label, I must scientifically figure out what the extended withdrawal period should be,” said Brick. “So when I come to your farm and treat an animal for pinkeye with a dose of penicillin that’s over-label, when I write down the withdrawal time, I can’t use the time that’s on the label because I used a higher dose. Make sure you have the proper withdrawal time from the vet.”
Some drugs are absolutely prohibited for use in food animals — ever. “If they find these drugs in an animal, you’re going to be in deep trouble,” said Brick, naming chloramphenicol, clenbuterol, diethylstilbestrol and nitrofurans (found in ointments for wound dressings).
Brick outlines the process he must observe as a veterinarian if he wants to prescribe something for other than what is written on the label. “Are the animals we’re going to treat food animals? Some of that depends on the state you’re in. In some states, alpacas are considered food animals. In most states, pot-bellied pigs are considered food animals. Sheep and goats, even backyard pet sheep and goats, are still considered food animals.
“I have to ask if there is a drug labeled for food animals with the proper ingredients and dosage, is it labeled for the indication, and is it effective?” said Brick. “If I can’t answer yes to those questions and find another drug, I have to ask if there is another drug that I can use extra-label to treat the condition. If the answer is no, I have to ask myself if there is another drug for non-food animals that could be used extra-label for this condition. For example, maybe there’s a horse drug I can use. If the answer to that is no, I ask if there’s a human drug that can be used extra-label.”
Brick explains the label on a medication is only valid for the bottle it’s on. For example, a bottle of penicillin is not the same as pen-G. “If the label directions state that the dose is 1 cc/100 pounds, according to the law, using any more than that is extra-label use and you have to have authorization every time you use it,” said Brick. “If you’re treating a group of cattle, that would be one time. If you treat more cattle tomorrow, unless there’s a prescription giving you a time frame that you are authorized to use that drug extra-label, or if there’s protocol written for that indication, you can treat for longer. Otherwise it’s a one-time thing.”
Veterinarians and producers are obligated to follow the duration of treatment as recommended on the label. For example, the label might state that the drug should not be used more than four consecutive days without reconsulting the veterinarian, who should review the animal’s condition. The bottle label will also include the withdrawal period. “But if you administer 5 cc/100 pounds, that 14-day withdrawal time has to be increased, and you can’t just multiply times five,” said Brick, adding that there is an organization that will calculate additional withdrawal time based on animal weight and other factors.
So what’s the bottom line for producers who are accustomed to purchasing common antibiotics without a veterinarian’s involvement? Have a good VCPR, always follow labeled instructions, consult your veterinarian if treatment is not working and watch for the new regulations from FDA.