29 Sept 2025
Scott Weese says changing human behaviour fundamental to tackling AMR, as “the human brain is the biggest issue with antimicrobial stewardship”.
Chris Simpson
Job Title
Image: encierro / Adobe Stock
A leading antimicrobial expert has urged vets to “treat patients, not lab results” to help combat the growing threat of antimicrobial resistance (AMR).
Scott Weese, director of the Centre for Public Health and Zoonoses and chief of infection control at Ontario Veterinary College’s Health Sciences Centre at the University of Guelph, delivered the Peter Rossdale Clinical Evidence Lecture at BEVA Congress.
His talk, “Misconceptions, myths and dogmas: moving past old barriers to optimise antimicrobial use in horses,” embodied the conference’s theme of “Use it wisely or lose it forever.”
Prof Weese argued changing human behaviour is fundamental to tackling AMR, as he explained: “The human brain is the biggest issue with antimicrobial stewardship.”
“We treat patients; we don’t treat lab results. We use lab results to guide us, but if you don’t trust your lab result, if you think it’s not represented that patient, you don’t have to treat it.”
Prof Weese, who was also the former chairperson of the World Health Organization advisory group for critically important antimicrobials in human medicine, noted vets “have a lot of ingrained approaches to antimicrobials” and “use them a lot by rote”.
He observed vets often fear being blamed if they do not use antibiotics or end a course early and an animal has a complication. He added: “Risk aversion hampers effective change. The ‘what if’ is a big problem. ‘It can’t hurt’ is a fallacy.”
He said animals’ value and owner insistence are “two serious risk factors for antibiotic use in animals” globally and that a large proportion of antibiotics are used as psychotherapeutics to make vets and owners feel better without benefiting the patient.
Prof Weese urged vets not to “get dogmatic with duration” of antibiotic courses because “a lot of the durations, if not almost all of them, are made up” based on fingers counted or days of the week.
He added: “If we were three-toed sloths, we’d be treating for three or six days, probably just as effectively, with less antibiotic resistance.”
Prof Weese also challenged the adage that if an antibiotic is started it needs to be continued for a minimum period to prevent resistance issues, which he said “makes absolutely no sense”.
He added: “How does [administering antibiotics] less cause more resistance? It doesn’t. I’ll buy you a beer if you can give me a plausible explanation for that.”
Overall, he said the goal to eliminate AMR will not happen, but “at the individual level, we can have an impact” and that lessening use can cause a decline in resistance.
Prof Weese added: “There is enough plausible reason to think that if we do a good job, we could make things better.
“A lot of it’s being brave, thinking about it, having the confidence and having the motivation to reassess our patients, and pull the drugs away when we don’t need them.”
The lecture was attended by the Princess Royal, who thanked BEVA “for taking on this practical lead on antibiotic microbial stewardship”, including through BEVA’s MonitorME antibiotic tracking programme.
Princess Anne added: “Good stewardship, for everybody’s perspective, does really need us to do more rather than just use less.
“And for you, that’s the challenge of choosing wisely: right medicine, right time, right dose, right patient.”
