As you know, the new antibiotic use regulations governing Veterinary Feed Directive (VFD) drugs and water medications took effect on January 1. The US Food and Drug Administration (FDA) enacted these changes in the regulation to enhance the stewardship of antibiotic use in food-producing animals and place that use under the oversight of the veterinarian. This action will likely focus additional attention on veterinarians and their role in the antibiotic decision-making process.

The FDA worked with drug sponsors to eliminate uses for growth promotion that the agency deemed “injudicious.” In addition, FDA modified the VFD as part of the agency’s overall strategy to promote the judicious use of antimicrobials in food-producing animals. The modified VFD rule places the authorization of feed-grade antibiotics considered medically important in human medicine under the supervision of a licensed veterinarian. It is the goal of the FDA to restrict the use of these medications so that they are used only when medically necessary to ensure animal health.

With the removal of production claims from antibiotic labels, it is likely more scrutiny will be placed on prevention and control uses. The modified regulations place additional emphasis on the necessity of establishing and maintaining a valid veterinary-client-patient relationship. All of these efforts are an attempt to facilitate veterinary oversight and enhance the prudent use of antibiotics in food-producing animals. A key provision in the effort to promote antibiotic stewardship is our ability to justify the decision to use antibiotics, the products we choose, and the manner in which those drugs are used.

An important aspect of antibiotic stewardship is the ability to use injectable, water soluble, and human drugs in an extra-label manner. The Animal Medicinal Drug Use Clarification Act outlines the mechanism by which veterinarians can prescribe antibiotics for extra-label use. Under certain circumstances, veterinarians are allowed to use drugs in an extra-label manner. There are, however, some drugs for which extra-label use is further restricted or banned entirely. Two of these drugs approved for use in swine include the cephalosporins and fluoroquinolones (eg, ceftiofur and enrofloxacin, respectively).

The extra-label use of the cephalosporins is limited to treating or controlling only those indications not included on the label. Cephalosporins may not be used for prevention of disease or in any manner (dose, duration, route of administration, etc) not specifically outlined on the label. The extra-label use of the fluoroquinolones is entirely prohibited. There is no legal justification for the extra-label use of fluoroquinolones. Also, remember, any extra-label use of feed-grade antibiotics remains illegal, even for veterinarians.

In addition to the extra-label use of antibiotics, veterinarians must ensure that all uses are necessary and justified to improve animal health, protect public health, and ensure food safety. If we are to continue to be viewed as the appropriate stewards of antibiotic use, we must ensure that these drugs are used in a judicious manner for the prevention, control, and treatment of disease within the legal limitations placed on their use.

Practices such as “routine use” and “pulse dosing” have come under additional scrutiny lately. The FDA responses to questions regarding these practices exhibit the agency’s expectations that antibiotic use should be considered a temporary solution rather than a long-term fix. The agency has expressed its interpretation that routine use should be re-evaluated to determine the continued need for antibiotics and that pulse dosing may not meet the intent of product approvals and labeling. In addition, the agency has raised concerns regarding the duration of use of some products which may have no specified duration of use on the label or are labeled for “continuous” use. Additional restrictions may be placed on products regarding duration of use claims or the establishment of labels defining duration of use in cases where none currently exists.

Unfortunately, determining judicious use and differentiating prevention or control is often easier said than done. There is a large grey area open for interpretation in these terms. Thus, it comes down to veterinary experience and training – the so called “art of practice.” First and foremost, veterinarians are the stewards of the health of the animals under our care and the promotion of public health.

Veterinarians are forced to balance animal health, public health, ethical use, economics, food safety, regulation, market challenges, and consumer perception. Having that many masters makes the task exceedingly difficult. The AASV continues to work with pork producers, researchers, allied veterinary organizations, drug sponsors, and the FDA to ensure the continued availability of antibiotics and to promote the appropriate and legal use of these products for animal health and public safety.

Harry Snelson, DVM Director of Communications