Drug changes not affecting pig health, so far

Drug, vaccine use adjusted before antimicrobial use restrictions increased
Published on April 12, 2017
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Federal controls over antibiotic access and use increased at the end of 2016, requiring veterinarian oversight of hundreds of drug applications.

Swine veterinarians said at a late February meeting in Denver that the change has required some adjustments in practices, but several veterinarians reached during and after the meeting indicated the changes have had no noticeable effects on pig health, so far.

Dr. Paul Ruen, a partner at Fairmont Veterinary Clinic in Fairmont, Minnesota, and a lecturer at the American Association of Swine Veterinarians’ annual meeting, noted in an interview after the meeting that raising a pig to market weight takes six months, so pigs on their way to market had started their lives before the restrictions took effect.

“Where there’s a need to use, we can still use antibiotics to treat,” he said. “It hasn’t been restrictive in the sense that, as long as we have access to those medications, we’re able to take care of a problem that shows up.”

He had lectured at the meeting on how his veterinary practice prepared for increased oversight of antimicrobial use through veterinary feed directives, which are similar to prescriptions. That involved increasing communication with feed mills, educating clients, and forming new administrative habits.

Veterinarian in a swine facility

In agreements with pharmaceutical companies, the Food and Drug Administration removed over-the-counter access to antimicrobials that were administered in livestock feed or water and are in the same drug classes the FDA considers important for human medicine, replacing that access with requirements for VFDs for antimicrobial administration in feed and prescriptions for administration in water. The agency also removed all production claims, such as growth promotion, for those drugs.

Drugs both considered important for human medicine and distributed through over-the-counter sales have accounted for about 60 percent of the volume, by weight, of all antimicrobials distributed for administration to livestock, according to FDA drug sales data from 2015, the most recent available.

Maintaining health

Cary Sexton, a practitioner from Deep Run in eastern North Carolina and an attendee at the AASV meeting, said outside the lecture halls that his four-veterinarian practice began making changes before the new year and tried to make the transition simple for clients. That included switching to feeds that would not require VFDs and increasing consultation on which medications were needed.

“What it really opened up for us was the ability to get back in the conversation about feed because it really had been handled by the nutritionists up to that point,” he said.

Dr. Sexton said antimicrobial use had been declining among finishing pigs for several years, and veterinarians had been increasing the use of vaccines against preventable bacterial diseases.

Like Dr. Ruen, Dr. Sexton said he had seen no major changes in swine health, but “It’s really a little bit early in the program to know what the long-term effect is.” He said the same is true about effects on antimicrobial resistance.

Dr. Liz Wagstrom, chief veterinarian for the National Pork Producers Council, also said she has heard of no health effects on pigs from the restrictions. She thinks people in the swine industry have been easing into changes in antimicrobial use over the past two years, adjusting vaccinations and other practices.

She also said veterinarians remain able to order antimicrobial administration to pigs in times of disease vulnerability or stress, which may have prevented the types of disease outbreaks seen as other countries implemented more restrictions on antimicrobial use. She said Denmark, in contrast, had a rise in post-weaning scours following prohibitions on antimicrobial prophylaxis during the late 1990s.

Increasing accountability

As veterinarians get used to the increased oversight of antimicrobial use, one of the lecturers at the AASV meeting predicted, their accountability will grow.

“More veterinarian responsibility is coming, not less,” Dr. Matthew Turner said. “The conditions of use for these drugs are going to be updated. There’s going to be a lot of education about antimicrobial stewardship practices in the future.”

Dr. Turner, head of operations for JBS Live Pork, said providing effective oversight of drugs will involve exceeding the minimum requirements of regulations. Veterinarians need to do better at monitoring and developing benchmarks for antimicrobial use, defining doses by biomass. They also need to maximize efficiency of those drug uses, he said.

“We’ve got an opportunity to improve health management practices,” Dr. Turner said. “We do. I do as a practicing veterinarian, and everybody in here does.

“We can all do a better job making decisions and improving our clinical skills.”

Doing what is right for pigs also may require advocating on the animals’ behalf to ensure antimicrobials remain available for disease prevention, Dr. Turner said. That is critical when dealing with, for example, Mycoplasma hyopneumoniae, which he said is causing chronic harm at the point when pigs show clinical signs of illness.

As herd sizes continue increasing, farms also need to learn how better to manipulate pigs’ immune systems, particularly through vaccination, he said. Rapid pen-side diagnostics also would aid medical decision-making.

Focusing more work on disease prevention promises to increase opportunities for some companies.

Dr. Michael Murphy, a veterinary medical officer with the FDA Center for Veterinary Medicine, talks during a panel Q&A session following a presentation series on antimicrobials. (Photo by Greg Cima)

Dr. Mark W. Bienhoff, who works in Des Moines, Iowa, for Kemin Industries and attended the AASV meeting, said his company is developing technologies that could, for example, keep pathogens out of livestock feeds, prevent water contamination, and disinfect rooms in farm buildings.

“Antibacterials, the typical things that veterinarians have always depended on, are going away—or their use will be a lot more limited,” he said.

Preventing the illness rather than treating a sick animal also increases profit, he said. Human medicine has been shifting toward prevention, and he thinks veterinary medicine is catching up. He sees that as a positive change.

Responsible antimicrobial use needs to involve an understanding of what drug resistances are present on a farm, according to Dr. Randall Singer, a professor of epidemiology in the Department of Veterinary and Biomedical Sciences at the University of Minnesota College of Veterinary Medicine, another AASV lecturer.

“If you don’t know that the population on your farm has or does not have certain resistances, you may just be making that situation worse,” he said.

Dr. Singer noted that drug resistance on a farm can be unrelated to drug use, as genes conferring resistance to one or more antimicrobials can be present in the absence of selection pressure from any antimicrobials. Humans did not create antimicrobial resistance but have added momentum to its proliferation, he said.

Dr. Michael Murphy, a veterinary medical officer with the FDA Center for Veterinary Medicine, said during one session on antimicrobials and a subsequent Q&A session that FDA investigators have been asked to phase in enforcement of the changes in antimicrobial availability and use, starting with an emphasis on education about the VFD rule.“There will be time in the future when we shift from education to compliance,” he said.

That time frame has not been announced. But he quoted a colleague in the CVM’s enforcement division as saying, “You only get one free tutoring lesson.”

Related JAVMA content:

Restrictions on medicated feeds coming to farms (Nov. 1, 2016)

Adjusting to reduced drug access, use (May 1, 2016)