Prospective randomised comparison of different antimicrobial protocols for the prevention of surgical site infections in horses undergoing emergency exploratory celiotomy

Abstract

Background: Surgical site infection (SSI) is an important complication following emergency celiotomy in the horse. Judicious antimicrobial use is important for the prevention of antimicrobial resistance and the limitation of antimicrobial-associated complications. Previous studies in horses have found no association between SSI and perioperative antimicrobial duration, but the ideal duration of antimicrobial administration in horses undergoing exploratory celiotomy remains unclear.

Objective: To compare SSI and describe post-operative complications, survival, duration and cost of hospitalisation in horses receiving one of two antimicrobial protocols following clean or select clean-contaminated emergency exploratory celiotomy.

Study design: Prospective randomised clinical study.

Methods: Adult horses undergoing clean or selected clean-contaminated emergency celiotomy at The University of Georgia Teaching Hospital (2013-2019) were prospectively enrolled and randomised to protocol A (pre- and intra-operative antimicrobials only, n = 39) or protocol B (antimicrobials continued for 72 h of post-operative administration, n = 37). Incisional closure and protection were standardised. The prevalence of SSI was compared between protocols for horses surviving beyond day five of hospitalisation and additional clinical outcomes were described.

Results: Horses in protocol A had an increased prevalence of SSI during hospitalisation compared with protocol B (6/37 [16%] vs. 0/35 [0%]; p = 0.03). The difference was of borderline significance at 4 weeks post-operatively (7/32 [22%] vs. 1/31 [3%]; p = 0.05).

Main limitations: Planned enrolment was not met, providing only enough data for a small study. Numbers were limited by inclusion criteria as well as difficulties regarding owner consent and surgeon-determined enrolment. In light of the low statistical power of the study, results should be used to direct further research, and caution must be taken in applying them to clinical practice.

Conclusions: The difference in hospitalised SSI between groups and the low prevalence of SSI, particularly in the 72-h post-operative group, supports the need for continued research to determine optimal antimicrobial duration and protocols to reduce SSI in horses undergoing exploratory celiotomy.

Keywords: antibiotic; colic; colic surgery; horse; prophylaxis.