Development of postoperative wound infection has historically correlated well with the National Research Council (NRC) classification of wounds, but predicting the likelihood of an individual to develop an infection is difficult. A wide range of data was evaluated in this retrospective study of 239 dogs and cats with clean-contaminated wounds (defined by the NRC as operative wounds of the respiratory, gastrointestinal, or genitourinary tract without unusual contamination in which a drain has been placed). These data were signalment, nutritional status, body weight, duration of surgery, surgical procedure, wound classification, surgical site clip time before surgery, hypotension during surgery, presence of an active distant infection, endocrinopathy, administration of an immunosuppressive agent, and administration of antibiotics and type used. Additional data included total surgery and anesthesia times, temperature variables, blood loss, suture material used, and gender status. Results showed that intact males and animals with concurrent endocrinopathy were at a higher risk for postoperative wound infection. As is true for clean wounds, longer surgery and anesthesia times were other predictive factors and should be reduced when possible. No other factors were found to be statistically significant, although such factors may exist and this subject should be studied further.

COMMENTARY: In this study, administration of antimicrobials was not shown to affect the incidence of postoperative wound infection in clean-contaminated wounds. Prophylactic/perioperative administration of antimicrobials should be considered in animals when prolonged surgical (> 90 minutes) and anesthesia times are anticipated and in patients with endocrinopathies or those that are otherwise immunocompromised. As in any surgery, the potential benefit of antimicrobial administration must be weighed against potential risks and side effects.

Epidemiologic evaluation of postoperative wound infection in clean-contaminated wounds: A retrospective study of 239 dogs and cats. Nicholson M, Beal M, Shofer F, Brown DC. VET SURG 31:577-581, 2002.