Evaluation of a stent dressing for anaesthetic recovery on surgical site infection following emergency equine laparotomy: A Randomised controlled trial

Background: Surgical site infection (SSI) is a frequent complication following emergency equine laparotomy. It negatively impacts equine welfare, increases treatment costs and is a hospital biosecurity risk justifying investigations of ways to reduce SSI incidence. Objectives: To determine if a sutured-on stent dressing for anaesthetic recovery reduces SSI in horses following emergency laparotomy. Study design: Randomised controlled trial. Methods: Eligible horses undergoing emergency exploratory laparotomy were enrolled. Horses were randomised to have a sutured-on stent dressing (intervention) or standard adhesive textile dressing (control) placed for incisional protection during anaesthetic recovery. Horses were followed up to 90 days postoperatively. Data were analysed according to intention-to-treat principles. Time to SSI (primary outcome) for each group was analysed using a Cox proportional hazard model. Secondary outcomes (SSI during hospitalisation, pyrexia during hospitalisation, days hospitalisation and incisional hernia formation at 90 days) were analysed using Chi-squared tests and a univariable logistic regression model (categorical data) or by comparing means between groups (continuous data). Results: The study included 352 horses (167 intervention group, 185 control group). SSI developed in 101 horses (28.7%) at a mean of 9.7 days (SD 4.6 days). Rate of SSI was not significantly different between intervention and control groups unadjusted (Hazard Ratio [HR] 0.83, 95% CI 0.56 - 1.23, P=0.36) or adjusted for variables significantly associated with rate of SSI (HR 0.88, 95% CI 0.59 – 1.30, P=0.51). There were no significant differences in secondary outcomes between intervention and control groups. Main limitations: This study was performed at a single centre and only evaluated incisional protection for anaesthetic recovery. Conclusions: Use of a sutured-on stent dressing for anaesthetic recovery did not reduce the rate of SSI compared to a textile adhesive dressing. Further RCT are required to investigate efficacy of other interventions on reduction of SSI following emergency laparotomy