Evidence reshapes antibiotic use for canine acute diarrhea

Routine antibiotic use for dogs with acute diarrhea is facing a clearer evidence check. Recent guidance from the European Network for Optimization of Veterinary Antimicrobial Therapy, published in The Veterinary Journal in July 2024, recommends against antimicrobials for dogs with mild or moderate acute diarrhea, including hemorrhagic cases, so long as there are no signs of systemic illness that persist despite fluid therapy. The shift reflects a broader body of research showing little clinical benefit from common empiric choices such as metronidazole or amoxicillin-clavulanate in uncomplicated cases, while reinforcing concerns about microbiome disruption and antimicrobial resistance. AVMA coverage of the same trend has underscored that most canine acute diarrhea cases are mild and are now better managed with supportive care such as rehydration, a highly digestible diet, fiber, and probiotics rather than default antibiotics. (wsava.org)

Why it matters: For veterinary professionals, this is less about a single new study than a practice change that’s been building for years. Randomized trials have found no statistically significant improvement in time to acceptable stool quality with metronidazole versus placebo in uncomplicated acute diarrhea, and a placebo-controlled trial of amoxicillin-clavulanate found no clinical benefit while documenting effects on the intestinal microbiome and resistant fecal E. coli. Survey data suggest prescribing habits still lag behind the evidence, with 21.2% of first-opinion veterinarians reporting antimicrobials as their preferred first-line therapy for canine idiopathic acute diarrhea. AVMA discussion of the issue points to a familiar disconnect: many clinicians endorse stewardship in principle but still reach for metronidazole out of habit, client expectations, and the urge to “do something” in a common, messy condition that is usually self-limiting. (pmc.ncbi.nlm.nih.gov)

What to watch: Expect more stewardship-focused protocols, decision aids, and continuing education that narrow antibiotic use to dogs with severe disease, suspected sepsis, or lab findings suggesting overwhelming inflammation. Just as importantly, expect more emphasis on practical supportive-care bundles for the roughly 90% of cases that present as mild—bright, alert dogs without fever, dehydration, or hypovolemia—so clinicians have a clear alternative to routine antibiotic prescribing. (wsava.org)