FDA vet offers guidance for syncing indications of mature VFD medications to today’s health problems

Part 3 in a series

In an exclusive 90-minute interview with editors from the VFD News Centers and Poultry Health Today, William Flynn, DVM, MS, deputy director for science and policy for FDA’s Center for Veterinary Medicine, clarified some hazy points of the new veterinary feed directive (VFD) regulations that took effect January 1, 2017. In this installment, Flynn talks about the challenges veterinarians sometimes face syncing indications of mature VFD medications to today’s health problems.

Q: Let’s talk about product labels. Dr. Flynn, as you know, many of today’s feed medications were registered more than 40 or 50 years ago. They’ve been used responsibly and, as a result, they’re still highly effective against a broad range of respiratory or enteric diseases. Yet, when these products were registered, poultry- and livestock-management practices, facilities and disease pressures were considerably different than they are today.

There are some diseases on these labels — atrophic rhinitis in pigs or swine dysentery, for example — that really aren’t big clinical problems in today’s herds. Similar situations exist for other species. By the same token, we’re aware that updating these labels would require a tremendous investment of resources by both the sponsors and FDA.

At long last, my question: If a poultry or livestock veterinarian is confident that the particular broad-spectrum antibiotic is going to be effective against the problem at hand but there’s not an exact match on the product label, what options do they have?

Is there any situation where a veterinarian could draw on his or her scientific training, experience and intuition of disease complexes and write a VFD if the suspected problem is somehow related to what’s on a product’s label?

How much latitude do veterinarians have in trying to connect the dots?

WF: Under the VFD regulations, veterinarians are limited to using that product according to the label — the specific indications of use and conditions of use that are outlined on that product label. In some cases, the labels are very, very specific regarding the indications for use and that limits the flexibility they have, but in other cases, the labels are a little bit broader.

Q: Let’s say we have pigs or chickens with an obvious respiratory or enteric problem and the veterinarian needs to do something quickly to manage the outbreak and relieve suffering.

The veterinarian is not exactly sure what pathogens are in play. But if he or she thinks that, say, tylosin or chlortetracycline might be effective, could the veterinarian look at the label and say, “Well, there’s a good chance that one of those bugs on the label is in there, so I’ll check this box and go on my gut feeling.”

Is that a reasonable course of action given the circumstances?

WF:  Yes, if they have a respiratory disease or a pneumonia case, for instance, and are reaching for a VFD drug that is approved in feed for treating respiratory disease or pneumonia in that animal, that would be acceptable. In these cases, we need to look to the veterinarian to use their clinical judgment. This goes back to that general or preliminary diagnosis in the VCPR that we spoke about earlier.

For VFD or prescription products, our main concern is that there’s veterinary oversight. That’s our primary objective — that the veterinarian is involved and is consulting with the producer and helping make decisions around the use of that product and selecting the product for the given circumstance, based on their judgment of that circumstance.

But again, there are some limitations. Because of the way the law is written, animal drugs administered in feed must be used according to the label indications.

Q: So, in summary, if a veterinarian is making a clinical diagnosis and wants to use a particular broad-spectrum antibiotic for a condition or pathogen that is, in their best judgement, potentially related to an indication on the product’s label, could they feel comfortable writing a VFD for that feed medication? 

WF: There is a legal obligation to use the product on label. Once again, I’ll use respiratory disease as an example. You may have Product A that’s approved for respiratory disease in cattle and Product B that’s approved for foot rot but not for respiratory disease. If they’re making a diagnosis of respiratory disease, then obviously, they need to be reaching for and authorizing the use of a product that has a respiratory disease on the label. They can’t authorize a product that only has a foot rot claim for treatment of respiratory disease.

But in terms of diagnosing respiratory disease, we’re not interested in second-guessing the veterinarian. The veterinarian needs to use clinical judgment to determine whether or not they are in fact dealing with respiratory disease.

Q: I don’t mean to belabor this, Dr. Flynn, but I just want to be clear for our readers. If there’s a respiratory disease in a flock or herd and there’s a particular antibiotic the veterinarian feels will be effective and it at least has one respiratory claim, the veterinarian in his or her clinical judgment and experience could feel confident issuing a VFD for that product. Is that correct?

WF: Yes, that’s accurate. Labels on these products are sometimes more specific and sometimes not. Some may specify respiratory disease associated with bacteria X, Y or Z. The veterinarian may not have confirmed diagnostics that prove its bacteria X, Y or Z, but if the clinical syndrome is one they feel, based on experience, is consistent with that respiratory disease and the history suggests it’s often associated with one of those bacteria, then, yes — I think that would be acceptable.

It’s not as though we’re saying a veterinarian is obligated to get more diagnostics if their clinical judgment leads them to believe this is the appropriate product to use.

Q: What about medically important water-soluble antibiotics?  Is there still an extra-label option for those?  And if not, would a veterinarian have the same clinical latitude that you described for medically important medicated feed additives that require a VFD?

A:  Our thinking would be the same in terms of veterinarians using their clinical judgment when‎ diagnosing disease and determining the appropriate treatment. However, there is more latitude legally regarding a scenario that involves a water-soluble antibiotic product. Current law permits a veterinarian to prescribe (under certain conditions) that a water-soluble product be used in an extra-label manner, but extra-label use of drugs in or on animal feed is not permitted.

Read the full interview.