Epidemiologic evaluation of postoperative wound infections in dogs and cats

OBJECTIVE: To determine postoperative wound infection rates in dogs and cats for various wound contamination categories and to identify factors that influence postoperative wound infection rates. DESIGN: Epidemiologic study. SAMPLE POPULATION: 1,574 wounds in 1,255 dogs and cats. PROCEDURE: Information recorded included signalment, nutritional status, surgery duration, surgical procedures, wound contamination classification, interval from clipping until surgery, blood pressure values, active infection at a distant site, endocrinopathy, and administration of immunosuppressive medications or antibiotics. Relative risk, 95% confidence intervals, and multiple regression analyses were performed. RESULTS: Postoperative infection was evident in 86 of 1,574 (5.5%) wounds, including 54 of 1,146(4.7%) and 13 of 259 (5.0%) animals with clean and clean-contaminated wounds respectively, and 12 of 100 (12.0%) and 7 of 69 (10.1%) animals with contaminated and dirty wounds, respectively. Animals with clean wounds that received antibiotics other than as prescribed in our perioperative protocol had a higher infection rate than animals that did not receive antibiotics. Surgical sites clipped before anesthetic induction were 3 times more likely to become infected than sites clipped after induction. Risk of wound infection increased with increasing duration of surgery. CLINICAL IMPLICATIONS: Wound contamination categories had too much variation to make them useful for predicting animals that would develop wound infections. Surgical sites should be clipped immediately prior to surgery, and intraoperative time should be kept to a minimum. Unless indicated for other current active infection, prolonged use of antibiotics after surgery should be avoided in animals with clean wounds.