Use antimicrobials responsibly, say veterinarians

Officials urge livestock industry to seek alternative treatments when possible to ward off criticism from the public

OLDS, Alta. — Bacteria showing resistance to antimicrobials is a complex and unpredictable problem.

It is also a natural phenomenon, but growing public pressure is forcing veterinarians and livestock producers to reconsider their use of antimicrobials.

Besides passing resistant bacteria into the food chain, many consumers worry about drug residues in meat.

Drug residues may appear when the animal was slaughtered too soon after receiving medication, but that should not be a concern in Canada, says a veterinarian.

“Residues or drugs in our meat is not an issue, whether it is from a conventional system or whether it was one raised without antibiotics,” Leigh Rosengren of Rosengren Epidemiology Consulting told the Banff Pork Seminar held Jan. 20-22.

As well, consumers need to understand that bacteria are everywhere.

The Canadian Integrated Program for Antimicrobial Resistance Surveillance, which is funded by the Public Health Agency of Canada, enters abattoirs and grocery stores searching for resistant bacteria on chicken, pork and beef. Positive samples have been found at low levels.

It does not mean antimicrobials should be removed from livestock production, but responsible use is needed to keep animals healthy.

“In my mind, they are an invaluable tool for agriculture,” Rosengren said.

“I will never be a proponent of a world without antibiotics in livestock. They are absolutely necessary to maintain the welfare of our animals.”

However, critics question whether it is responsible to use antibiotics in feed and water to prevent disease and improve average daily gain and feed efficiency.

Healthy animals grow faster, said Sherry Hannon, a veterinarian and epidemiologist with Feedlot Health Management Services at Okotoks, Alta.

“In some cases, we are also using antimicrobials to improve average daily gain and feed efficiency where there may not be much impact on health,” she said at a special workshop on antibiotic use and pain management in Olds Jan. 27.

“That is where people are having more of a problem with our responsible use.”

Europe does not allow antibiotics for growth promotion, and the U.S. Food and Drug Administration compelled pharmaceutical companies to voluntarily pull these products off the market beginning in 2013. Full compliance is expected this year.

Rosengren said Canada needs to keep its regulations aligned with the United States.

However, fewer approved products are available in Canada, and pharmaceuticals are often used to treat conditions or species not mentioned on the drug company label. No one wants to end extra label use, she said.

Canada also allows over the counter purchases of products, but that could change to a prescription only rule.

Prescriptions are required in Quebec and Newfoundland, but the other provinces have different rules. These products come under federal jurisdiction in the U.S.

Hannon also recognizes the public view of antibiotic use. She regularly prescribes antimicrobials, but her practice is looking for ways to reduce the use of these drugs, including alternative treatments.

“At this moment, we haven’t found a lot of really practical ways to replace our antimicrobials. If we were, we would be using them,” she said.

The treatment plans at her feedlot practice are based on risk for diseases such as bovine respiratory disease.

For example, a 700 pound vaccinated steer might be considered lower risk than a newly weaned 300 pound calf arriving at a feedlot. The calf will receive antibiotics upon arrival to get ahead of potential disease.

Her practice also documents what was done to individual animals. Pressure will continue for the entire industry to record and track which animals were treated, why, when and how well they recovered, she said.

Written records should improve understanding of which microbes are appearing and which drugs were most effective. It could also track prevalence and changes over time.

Research is also critical to track outcomes and the prevalence of resistant microbes.

“We need to have the data to show what is happening,” she said.

Feedlot Health Services ran a three year study to learn the prevalence and susceptibility of Mannheimia haemolytica, a bacterium responsible for BRD.

The study, which subjected the samples to 21 antimicrobials, found that 87.8 percent of the isolates were pan susceptible to antimicrobials and 5.9 were multi resistant.

The industry is aware of the problem of antimicrobial resistance and is behaving responsibly, said Rosengren.

Most producers work to prevent infections and spread of disease with vaccination, good hygiene, proper nutrition and controlled animal movement.

Producers also need to talk with their veterinarians to decide if antibiotics are necessary or beneficial, she added.

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