Evaluation of long-term postoperative morbidity and survival after equine colic surgery using a complication severity classification

Background: Most studies on colic surgery outcome focus on short-term survival and complications. Long-term outcomes, particularly post-discharge morbidity, are poorly characterised despite their relevance. No standardised system has previously integrated both short- and long-term postoperative complications with survival outcomes. Therefore, this study aimed to evaluate long-term survival and morbidity in horses after colic surgery using the equine postoperative complication score (EPOCS), and to assess the association between complications and survival. Methods: The medical records of horses undergoing colic surgery between January 2017 and March 2021 were retrospectively reviewed. Long-term follow-up (≥4 years) was obtained via telephone. Complications were scored using the EPOCS. Results: Of the 244 horses undergoing surgery, 203 were discharged, and 176 were successfully followed up. Post-discharge complications occurred in 44.8%, with colic being the most common. Pre-discharge EPOCS was negatively correlated with long-term survival (r = –0.25, 95% confidence interval [CI]: –0.40 to 0.09, p = 0.002). Total EPOCS was also inversely associated with survival (r = –0.19, 95% CI: –0.35 to –0.02, p = 0.02). Post-discharge EPOCS was not associated with survival. Lesion type, intestinal segment and resection did not significantly affect survival. Limitations: The retrospective design, owner-reported follow-up and single-centre data limit generalisability and underrepresent minor complications. Conclusions: Long-term survival in horses with colic is favourable; however, postoperative complications are common and prognostically relevant. EPOCS provides a structured method for quantifying morbidity and may support future comparisons between surgical techniques and management strategies.