When public health talks in the U.S. turn to antibiotic resistance, the conversation invariably leads to the use of antibiotics in food animals. The Food and Drug Administration (FDA) has confirmed that 80 percent of antibacterial drugs in the U.S. are sold for agricultural use. And Department of Agriculture (DOA) surveys have found that 83 percent to 84 percent of swine farms, cattle feedlots and sheep farms administer antimicrobials in feed or water, which can lead to inconsistent dosing. Many of those drugs are identical or closely related to human drugs.

In newly released voluntary guidance likely to significantly limit such use of antimicrobial drugs, the FDA cites numerous peer-reviewed scientific studies, along with a host of reports dating back to 1969 from groups including the World Health Organization and the Institute of Medicine, suggesting a relationship between the injudicious use of antibiotics in food-producing animals and antibiotic resistance.

Industry groups have countered the FDA with numbers that downplay the link. But Sean Minahan, a partner at Lamson, Dugan and Murray in Omaha, Neb., says that whether the FDA’s findings are right or wrong, at this point the momentum is in its favor. The research to support limitations on antibiotic use in animals is building, the Obama administration supports such limits and the organic and all-natural food movements are huge and growing.

On April 11, the FDA released three documents addressing the responsible use of medically important antibiotics in food-producing animals. Implementation of these policies would eliminate nontherapeutic uses of medically important antibiotics in animal agriculture and require veterinary supervision of therapeutic uses.

“That is a major change, and it is a policy that would align animal-health uses of antibiotics with the way they’re used in human health,” says Ron Phillips, vice president for legislative and public affairs for the Animal Health Institute (AHI), an industry group that represents animal drug developers and producers.

Limited Use

The FDA’s April guidance eliminates all nontherapeutic uses of antibiotics in food-producing animals, limiting use to what is “considered necessary for assuring animal health,” which it specifically limits to treatment, control and prevention. It also directs that antimicrobials—which for decades have been available over-the-counter to livestock producers—now should be used only with veterinary oversight or consultation.

Antibiotics the FDA has approved for animal use currently fall under four label claims—treatment, control, prevention and growth promotion, or the claim that use of a drug leads to greater growth with less feed. The guidance eliminates this last claim (see “Label Changes”).

Nontherapeutic use of antibiotics is common among livestock producers, who administer low-level doses of antibiotics to entire herds or flocks of animals for long durations, usually through feed, without targeting any specific disease. Low doses of antibiotics are linked to resistance. Given such long-term and widespread use, the FDA says growth promotion represents a substantial proportion of the overall use of antibiotics in agriculture, although it has no specific data.

There has been some concern among public health groups over the FDA’s continued approval of antibiotics for preventive use. Dr. Robert S. Lawrence, professor at the Johns Hopkins Bloomberg School of Public Health, wrote in a piece for The Atlantic that like growth promotion, preventive use involves low doses “that are equally culpable in the development of antibiotic resistance.” The FDA maintains that in some cases preventive use is “necessary and judicious” under veterinary supervision.

Public health groups also have expressed concern that the guidance is voluntary rather than compulsory.

“In the FDA world, ‘voluntary’ means something different,” Phillips rebuts. “The guidance means that this is the FDA’s approach, and basically that if you want to work with the FDA, this is the way you’re going to do it.”

The FDA has said it will assess adoption levels after a three-year period.

Veterinary Demand

The FDA calls for veterinarians to supervise use of antibiotics that go into animal feed and requires a statement from them stipulating details of use—how long it is given, how much is administered and how it’s distributed among herds, for example. “It becomes very cumbersome, almost tedious,” Minahan says of the process. Livestock producers fear their operating costs will grow substantially because of an increased need for veterinary oversight. What’s more, Minahan says, the increased demand for veterinary supervision could cause a shortage of care. In many regions, large-animal veterinarians are hard to find in the first place.

“For small producers who don’t have a vet on staff … or even those in really remote areas without easy veterinary access, this has the potential to be a big issue,” says Liz Wagstrom, chief veterinarian for the National Pork Producers Council.

Livestock producers also fear that by limiting the use of antibiotics, instances of illness and disease in animals will rise, which would lead to producers treating them with antibiotics in higher dosages than would have been used for growth promotion. “Is it better to use a low dose in an entire population or to use increased doses at select times? The science gets hazy here,” Minahan says.

Continuing Trend

Not all producers oppose or fear the changes. Stephen McDonnell, the founder and CEO of Applegate Farms, an organic meat and cheese producer that works with a network of nearly 1,000 family farmers, says his company has seen success and growth over 25 years using an antibiotic-free model. “Producers need to look at these changes as an opportunity, not a challenge,” he said in an email.

Wagstrom advises that producers do anything they can to improve management, which is how Danish producers say they survived the country’s similar 1998 ban on nontherapeutic use.

The FDA’s April guidance is another step in its evolving approach toward antibiotics use in livestock. In January, it took the small step of banning certain off-label animal uses of cephalosporins, a class of antibiotics used in both animals and humans. Minahan says that ban got the ball rolling.

“I tell my clients to plan ahead and start transitioning their production [according to what] they think the FDA’s going to do in the future,” Minahan says. “Unless you come up with something that shows antibiotics are not creating antibiotic-resistant bacteria, you’re going to have a hard time reversing this trend.”