What is the preferred surgical approach for septic vs non-septic pyometra and how do I manage perioperative risks?

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Ovariohysterectomy (OVH) is the preferred treatment for canine pyometra in all cases, regardless of septic status, with the critical distinction being how aggressively the patient must be stabilized before induction.34 For septic or systemically ill patients, presurgical stabilization with IV fluid therapy and broad-spectrum antimicrobials is required before anesthesia.3 Systemic inflammatory response syndrome (SIRS) or sepsis is present in more than 50% of dogs with pyometra, and left untreated, SIRS can progress to multi-organ dysfunction syndrome and death.15 Despite this, mortality rates after OVH remain low — reported at 1% in one series and 3–10% in others — and overall prognosis after successful surgery is excellent.15 For non-septic, stable patients, the same surgical approach applies, and the perioperative risk profile is substantially lower. Mortality in a cohort where all dogs were confirmed stable enough for concurrent mammary tumor removal was 0%.5 Laparoscopic-assisted OVH (LaOVH) is an option in select pyometra cases, but patient selection is critical: uterine diameter must be below 2 cm in dogs under 10 kg, and below 4 cm in larger dogs, to be considered safe for the minimally invasive approach.2 No outcome advantage of LaOVH over open surgery has been demonstrated in pyometra specifically.2 The major perioperative infectious complications to anticipate are surgical site infection (SSI) and urinary tract infection (UTI). SSI rates after clean-contaminated procedures range from 3.5% to 6.6%.1 Concurrent cystitis has been reported in 5.6–71% of dogs with pyometra, and in most of those cases the urinary bacterial isolates matched the uterine isolates — implicating ascending E. coli as the predominant pathogen in both sites.1 E. coli is the most common causative organism in pyometra overall.1 Ovary-sparing hysterectomy is not recommended for pyometra — while it has been proposed for individuals at high risk from the hormonal consequences of spaying, it h