Veterinarians are frequently prescribing metronidazole in contradiction to antimicrobial use guidelines, new study finds

Metronidazole is commonly being prescribed to dogs and cats for reasons other than its antimicrobial properties, and frequently in contradiction to antimicrobial use guidelines

Metronidazole is commonly being prescribed to dogs and cats for reasons other than its antimicrobial properties, and frequently in contradiction to antimicrobial use guidelines, according to new research published in the Journal of Small Animal Practice.

Led by clinicians from Davies Veterinary Specialists, the Royal Veterinary College, and Willows Veterinary Centre and Referral Service, the study assessed the proportion of metronidazole use that was prescribed for non-antimicrobial purposes, and the rationale for it.

A survey was completed by 138 veterinarians, primarily in the UK and working in primary care small animal practice, who treated 332 cases (285 dogs and 47 cats) with metronidazole.

In 42% Of cases, metronidazole was selected exclusively for non-antimicrobial targeted therapy, and was most commonly prescribed to treat acute diarrhoea, chronic diarrhoea, or giardiasis. This is despite recommendations that antimicrobials are very rarely warranted for the management of acute and chronic diarrhoea.

The rationale cited by vets to justify metronidazole use in the study was most frequently its supposed anti-inflammatory or immunomodulatory properties. Treatment of suspected or confirmed anaerobic or susceptible bacterial infection; the patient being systemically unwell or having severe disease; treatment of protozoal infections; experiencing a previous positive outcome in a similar case or the same patient; anti-diarrheal action; and owner or practice expectations were other reasons offered.

Dr Justin Ng, lead author of the study, said: “These insights are alarming given that such practices frequently deviate from current antimicrobial use guidelines, potentially contributing to ongoing challenges with antimicrobial resistance and adverse effects on gastrointestinal health.”

These findings have important implications for antimicrobial stewardship. Future stewardship programmes should prioritise advocating the use of non-prescription forms (such as the BSAVA no antibiotic required ‘non-prescription’ form) so that antimicrobial treatment can be optimised (and minimised), adapting guidelines to tackle inappropriate prescribing of metronidazole, and developing educational resources that directly target these specific rationales for metronidazole use.

You can access the full study at: https://onlinelibrary.wiley.com/doi/10.1111/jsap.13910