Intravenous lidocaine and small-intestinal size, abdominal fluid, and outcome after colic surgery in horses.

Twenty-eight horses with the diagnosis of an intestinal disorder requiring surgical intervention were randomly assigned to lidocaine (n = 13) or saline (control, n = 15) treatment groups. After induction of anesthesia, treated horses received a loading dose of 2% lidocaine (0.65 mg/kg) intravenously, followed by a continuous rate of infusion of 1% lidocaine (0.025 mg/kg/min) until the discontinuation of anesthesia. Upon recovery from anesthesia, a 2nd loading dose of 2% lidocaine (1.3 mg/kg) was administered, followed by an infusion of 1% lidocaine (0.05 mg/kg/min) for 24 hours postoperatively. The control group received equivalent volumes of saline. Lidocaine-treated horses had significantly better minimum jejunal cross-sectional area scores (P = .011), minimum jejunal diameter scores (P = .002), and intestinal ultrasound index (IUI) (P = .007). Peritoneal fluid was detected by percutaneous ultrasound examination in 8 of the 15 control animals but in none of the treated animals (P = .003). Failure to obtain fluid via abdominocentesis was significantly more frequent for lidocaine-treated horses (P = .025). No significant differences between the groups were found in the presence of gastrointestinal sounds, time to passage of 1st feces, number of defecations in the 1st 24 hours, presence of gastric reflux, duodenal or jejunal wall thickness, maximum duodenal or jejunal diameter or cross-sectional area, minimum duodenal diameter or cross-sectional area, duodenal and jejunal intraluminal echogenicity, small-intestinal contractions per minute, rate of complications, or outcome. On the basis of this study, lidocaine infusion may have some desirable effects on jejunal distension and peritoneal fluid accumulation and was well tolerated perioperatively in horses with colic. The low incidence of small-intestinal lesions and gastric reflux in the study makes it difficult to assess the use of lidocaine in the prevention of postoperative ileus (POI).