Title:
Post operative infection, pyrexia and perioperative antimicrobial drug use in surgical colic patients.

Abstract:
Infections are common complications in post operative colic patients. It is the impression of some surgeons that pyrexia in the early post operative period is a sign of infection and appropriate timing of perioperative antimicrobials will decrease the incidence of post operative infection.
To determine the association between 1) post operative pyrexia and development of infection and 2) perioperative antimicrobial drug use and infection rate in post operative colic patients.
Medical records of patients undergoing surgical treatment for colic were reviewed. Horses recovering from surgery and surviving >48 h were included. Data relating to case details, duration of surgery, post operative infection, peri- and post operative antimicrobial administration, presence, intensity and duration of pyrexia, were recorded. Data were analysed using standard statistical methods for simple comparisons between groups and by logistic regression for more complex comparisons.
One-hundred-and-thirteen horses were included in the final analyses, 48 (43%) of which were diagnosed with a post operative infection. Duration of surgery and anaesthesia were associated with post operative infection. Eighty-five percent of horses (n = 96) exhibited pyrexia (rectal temperature >38.3°C) post operatively. Peak temperature >39.2°C, time post surgery to peak temperature >48 h and duration of pyrexia >48 h were significantly associated with infection. In a combined model, time to first pyrexic >48 h post surgery, peak temperature and time to peak >48 h were equally weighted and the model's positive predictive value for post operative infection was 72%. Timing and dose rate of preoperative antimicrobials were not associated with infection but duration of post operative antimicrobial drug use was.
Slight to mild pyrexia (38-39.4°C) in the early post operative period is not necessarily associated with impending bacterial infection in colic patients and the use of antimicrobials in these patients may be costly and unnecessary.