A retrospective evaluation of the effect of perianesthetic hydromorphone administration on the incidence of postanesthetic signs of colic in horses

Abstract Objective To describe the incidence of postanesthetic signs of colic (PASC) in horses and determine if perianesthetic administration of hydromorphone was associated with an increased risk of PASC. Study design Retrospective, cohort study. Animal population A total of 409 horses. Methods Anesthesia and clinical records of horses admitted for various procedures from July 2018 to September 2019 were reviewed. Signs of colic and interventions were recorded up to 48 hours after anesthesia. A binomial logistic regression model was used to evaluate the association between the type of surgery, administration of hydromorphone, the duration of anesthesia and the incidence of PASC. Results Overall, 25 (6.1%) of horses developed PASC within 48 hours of general anesthesia. Of 60 horses that underwent colic surgery, 16 (26.7%) developed PASC. The incidence was higher than the nine of 349 (2.6%) horses not anesthetized for colic surgery that demonstrated PASC [odds ratio (OR) = 13.74 (5.73–32.95)]. No effect of hydromorphone on the incidence of PASC was identified [OR = 1.61 (0.71–3.62)]. Longer procedures (>2 hours) were identified as an independent risk factor for PASC [OR = 4.13 (1.52–11.22)]. Conclusions No association between hydromorphone and an increase in the incidence of PASC was identified. Anesthesia for colic surgery and duration of anesthesia were associated with an increased risk of PASC. Clinical relevance Hydromorphone did not increase the incidence of PASC in this population.