Uncomplicated acute diarrhoea in dogs: amoxicillin-clavulanate vs placebo — POSSIBLE (the treatment made no difference)

In dogs with uncomplicated acute (non-haemorrhagic) diarrhoea, does amoxicillin-clavulanate improve clinical recovery vs placebo, and at what resistance cost?

Shelf #162 · gate-verified and displayed under the developer's blinded-trial rule

POSSIBLE (the treatment made no difference): In the one randomised, double-blinded, placebo-controlled trial of amoxicillin-clavulanate in uncomplicated acute diarrhoea, treated dogs recovered no faster than dogs given placebo — every dog in both groups was back to a normal clinical score within 1 to 6 days — while amoxicillin-resistant E. coli rose to a median of 100% of faecal isolates during treatment and was still elevated 3 weeks after it ended (Werner 2020). Sixteen dogs is a small base, so a modest benefit cannot be formally excluded; but the trial found no hint of one, the natural course was recovery in days either way, and the resistance cost was measured directly in the same animals. This is a single-trial shelf, stated on its face. Drafted Nov 10, 2026 (VetMed build, topic #162); all figures from abstracts fetched and verified at drafting.

Werner 2020: no clinical benefit from amoxicillin-clavulanate in uncomplicated acute diarrhoea — but resistant E. coli rose to a median of 100% during treatment

Prospective, randomised, double-blinded, placebo-controlled study

Who: Dogs: 16 client-owned dogs with uncomplicated acute diarrhoea of <3 days' duration, randomly assigned to amoxicillin-clavulanic acid or placebo; recovery tracked with the CADS clinical index, the faecal microbiome by quantitative PCR, and amoxicillin-resistant E. coli semiquantitatively.

Result: No difference in clinical recovery: CADS index at day 10 was median 2 (range 1–3) in the antibiotic group vs median 1.6 (range 1–3) on placebo (P > .99), and all dogs reached a normal clinical score (CADS ≤3) within 1 to 6 days (median 2 days) after presentation. The faecal dysbiosis index did not differ significantly between groups. The resistance cost was clear: amoxicillin-resistant faecal E. coli rose to a median of 100% (range 35%–100%) during treatment vs a median of 0.2% on placebo (P < .001), and remained higher 3 weeks after treatment ended (median 10%, range 2%–67%, vs 0.0%; P = .002).

Watch out: Sixteen dogs is small, so the trial cannot exclude a modest clinical effect — but recovery was rapid and identical without the antibiotic, and the resistance harm was measured in the same dogs. This shelf rests on this single trial; the placebo trial in acute haemorrhagic diarrhoea syndrome is a different question (topic #161), not a second card here.

Werner M, Suchodolski JS, Straubinger RK et al. Effect of amoxicillin-clavulanic acid on clinical scores, intestinal microbiome, and amoxicillin-resistant Escherichia coli in dogs with uncomplicated acute diarrhea. J Vet Intern Med. 2020;34(3):1166-1176. PMID: 32324947. Registry ID: none in the record. MeSH: Amoxicillin · Amoxicillin-Potassium Clavulanate Combination · Animals · Anti-Bacterial Agents · Diarrhea · Dog Diseases · Dogs · Drug Resistance, Bacterial · Escherichia coli · Gastrointestinal Microbiome · Microbial Sensitivity Tests · Prospective Studies

Synthesis: no benefit shown, a measured resistance cost — the stewardship answer for uncomplicated acute diarrhoea

Synthesis

Who: Synthesis of the card above: Werner 2020 (randomised, double-blinded, placebo-controlled, 16 dogs) — the only placebo-controlled trial of amoxicillin-clavulanate in uncomplicated acute diarrhoea found for this shelf.

Result: The single trial answers both halves of the shelf's question: no clinical benefit (identical recovery, all dogs normal within 1–6 days on placebo too) and a real resistance cost (resistant E. coli at a median of 100% during treatment, still elevated 3 weeks later). The trial's own conclusion matches the international guideline position its authors cite: dogs with diarrhoea should not receive antimicrobials unless there are signs of sepsis. What would change this shelf is a larger placebo-controlled trial showing faster recovery — none was found.

Watch out: A null result in 16 dogs is moderate, not decisive, evidence of no benefit — hence POSSIBLE rather than a stronger stamp — while the resistance finding within the trial was large and statistically firm.

Synthesis of Werner M et al. PMID: 32324947. Registry ID as on the individual card.

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