Work

Placebo is non-inferior to postoperative antimicrobial treatment in uncomplicated canine pyometra – A double-blinded randomized controlled trial

Year: 2025

Type: article

Abstract: Postoperative antimicrobial therapy is frequently administered after surgical treatment for pyometra in dogs, despite limited evidence supporting its necessity in uncomplicated cases. Antimicrobial resistance concerns call for re-evaluation of such practices. This randomized, double-blinded, placebo-controlled, non-inferiority clinical trial was conducted on client-owned dogs at the Veterinary Teaching Hospital of the University of Helsinki. All dogs received perioperative sulfadoxine-trimethoprim prophylaxis and were then randomized to receive either placebo or a five-day course of oral sulfadiazine-trimethoprim as active control. The primary outcome was the incidence of surgical site infections (SSI) within 30 days; the secondary outcome was the incidence of clinical urinary tract infections (UTI) within 12 days. The non-inferiority margins were set at 7% (SSI) and 15% (UTI). Infection outcomes were assessed in both the intention-to-treat (ITT) and per-protocol populations (PP). A total of 152 dogs were included. In the ITT population, SSI incidence was 2.7% in the placebo group and 7.8% in the sulfadiazine-trimethoprim group, with an absolute difference of –5.1% (CI 95% : –13.6% to 2.8%). UTI incidence was 0% in the placebo group and 3.9% in the sulfadiazine-trimethoprim group (difference -7.7%, CI 95% : –24.1% to 8.2%). Results in the PP were similar. All findings supported the non-inferiority of placebo. A single perioperative dose of sulfadoxine-trimethoprim appears sufficient for preventing postoperative infections in this low-risk surgical population. • A randomized, placebo-controlled non-inferiority trial was conducted in 152 dogs with uncomplicated pyometra. • Placebo was non-inferior to postoperative sulfadiazine-trimethoprim in preventing surgical site and urinary tract infections. • No urinary tract infections occurred in the placebo group, even among dogs with perioperative bacteriuria. • Findings support abstaining from postoperative antimicrobial use in selected low-risk surgical patients.

Source: The Veterinary Journal

DOI: 10.1016/j.tvjl.2025.106449