Serial Postoperative Blood and Peritoneal Fluid Analysis and Ultrasonographic Assessment in Client-Owned Horses Undergoing Ventral Midline Exploratory Celiotomy for Colic.

Postoperative monitoring, including evaluation of peritoneal fluid, is used to aid in the diagnosis and treatment plan for complications after colic surgery. The primary objective of this study was to determine serial venous and peritoneal postoperative variables, including L-lactate values in horses after ventral midline exploratory celiotomy. A secondary objective was to evaluate postoperative abdominal ultrasonography as a predictor of complications. A total of 36 client-owned horses with signs of colic undergoing ventral midline exploratory celiotomy were prospectively enrolled in the study. Peripheral venous blood and peritoneal fluid were obtained, and abdominal ultrasonographic examination was performed preoperatively (T0) and at 48 h (T1), 72 h (T2), and 120 h (T3) postoperatively. Postoperative ultrasonographic examination suggested a normalization in postoperative small intestinal diameter, both in horses that experienced complications and those that did not. Peripheral L-lactate at T0, T1, T2, and T3 was 1.9 mmol/L (±1.5), 0.9 mmol/L (±0.5), 0.8 mmol/L (±0.3), and 0.9 mmol/L (±0.3), respectively. Peritoneal L-lactate at T0, T1, and T2 was 3.8 mmol/L (±2.4), 2.8 mmol/L (±1.8), and 1.1 mmol/L (±0.9). T3 was unable to be evaluated due to insufficient fluid. Of the 32 horses that survived to discharge, 25/32 experienced postoperative complications. The most common complication was postoperative colic. Postoperative peritoneal L-lactate was higher than blood L-lactate, even in horses without postoperative complications. Postoperative blood L-lactate was higher across all timepoints in horses with complications. This study was limited by the small number of cases.