Retrospective evaluation of the effect of xylazine infusion on survival to discharge in horses undergoing exploratory laparotomy for colic.

Abstract

OBJECTIVE: To determine the influence of xylazine infusion on survival to discharge and describe the associated intraoperative requirement for isoflurane, use of positive inotropes and vasopressors, and recovery time in horses undergoing exploratory laparotomy. STUDY DESIGN: Retrospective cohort study. ANIMALS: A total of 352 horses. METHODS: Medical records of horses undergoing anesthesia for exploratory laparotomy from January 2018 to December 2023 were reviewed. Data collected included survival to discharge, results of diagnostic tests, end tidal isoflurane concentration (FE'Iso), use of vasopressors/inotropes, and duration of recovery in horses with (WX) or without (WOX) intraoperative xylazine infusion. For survival to discharge, univariable and multivariable logistic regression was performed adjusting for the effects of other infusions. For all other variables, descriptive statistics were performed. RESULTS: Survival to discharge was 80.6% and 78.5% for WX and WOX, respectively (p = 0.431). Mean ± standard deviation FE'Iso was 0.82 ± 0.21% and 0.94 ± 0.21% for WX and WOX, respectively. Dobutamine was given to 159/166 (95.8%) and 176/186 (94.6%) horses at a rate of 1 (0.1-3.0) μg kgminuteand 1 (0.25-3.0) μg kgminutein WX and WOX, respectively. Norepinephrine infusion was given to 15/166 (9%) and 27/186 (15%) horses at a rate of 0.2 (0.025-0.4) μg kgminuteand 0.2 (0.05-0.7) μg kgminutein WX and WOX, respectively. Median (range) recovery times were 70 (15-310) minutes and 75 (20-313) minutes for WX and WOX, respectively. CONCLUSIONS: The use of xylazine as a part of a balanced anesthesia protocol in horses undergoing exploratory laparotomy did not negatively affect survival to discharge. CLINICAL RELEVANCE: Xylazine infusion as part of a balanced anesthesia protocol appears promising based on this single-center study. Further research is required to fully explore the risks and benefits of xylazine infusions in this context.