Abstract
Postoperative pain and ileus remain among the most impactful complications seen after exploratory laparotomy in horses, often contributing to longer hospital stays, increased morbidity and, in some cases, poorer outcomes. Abdominal pain following surgery arises from several overlapping factors, including tissue inflammation, distension and the handling of the intestines during the procedure. Postoperative ileus (POI), on the other hand, develops through a combination of sympathetic activation, inflammatory mediator release, ischemia–reperfusion injury and the mechanical effects of surgical manipulation. These pathophysiological processes tend to amplify one another, creating a postoperative state in which effective pain control and the recovery of normal gastrointestinal motility become central to a successful outcome. Intravenous (IV) lidocaine has attracted considerable attention because of its wide range of pharmacological actions, offering systemic analgesia together with anti inflammatory, anti ischemic and neuromodulatory actions, and a possible prokinetic effect on intestinal motility. As a result, lidocaine infusions have become a common component of perioperative care in many equine hospitals, particularly for horses undergoing surgery for small intestinal disease, where the risk of POI is highest. This review critically examines the current evidence regarding the pharmacology, clinical efficacy, and safety of IV lidocaine in horses undergoing laparotomy for colic, with particular attention to the factors underlying the variability in reported outcomes. The available literature does not point in a single direction. Several studies report better gastrointestinal motility, reduced reflux and improved postoperative comfort, suggesting that lidocaine may help counter both inflammatory and neural contributors to POI. However, other well designed clinical studies have not found clear improvements in motility or a reduction in the incidence of POI. These discrepancies appear attributable to differences in lesion type and severity, dosing protocols, infusion duration, and the absence of standardized diagnostic criteria for POI. Although lidocaine is generally safe at recommended plasma concentrations and consistently provides analgesic and anti inflammatory effects, its exact contribuition to preventing POI is still not fully established. Future research should focus on developing standardized POI definitions, harmonized dosing protocols and prospective trials that account for lesion type, so that the clinical situations in which lidocaine is most beneficial can be clearly identified.

Key words: Analgesia; Colic; Equine; Lidocaine; Postoperative ileus.