CARDIOPULMONARY AND GASTROINTESTINAL MOTILITY EFFECTS OF XYLAZINE KETAMINE-INDUCED ANESTHESIA IN HORSES PREVIOUSLY TREATED WITH GLYCOPYRROLATE/

Objective-To assess the usefulness of glycopyrrolate (GLY) in preventi ng the decrease in cardiac index (Cl) usually caused by xylazine (XYL) /ketamine (KET)-induced anesthesia in horses. Animals-6 healthy horses . Procedure-Horses were treated with saline solution or 2.5 mu g of GL Y/kg of body weight, administered IV. 15 minutes later, XYL (1 mg/kg) was administered IV, followed 5 minutes later by KET (2 mg/kg) adminis tration. The horses were positioned in left lateral recumbency, insuff lated with 15 L of oxygen/min, and maintained for 30 minutes on the in fusion of 0.05 mg of XYL and 0.1 mg of KET/kg/min. Mean, systolic, and diastolic arterial blood pressures, mean pulmonary arterial and centr al venous pressures, heart rate, Cl, and arterial and mixed venous blo od gas tensions were recorded up to 40 minutes after anesthesia induct ion. Intestinal motility was assessed by auscultation of 4 abdominal q uadrants for 24 hours after induction. Data were analyzed by Wilcoxon' s rank-sum lest for nonparametric observations, and by ANOVA for repea ted measures and Scheffe's test for continuous parametric variables. R esults-Horses given GLY had significantly higher heart rate; mean, sys tolic, and diastolic arterial blood pressures, Cl; oxygen delivery; an d mixed venous oxygen tensions, with significantly less tissue oxygen extraction, compared with saline-treated horses. Both groups had compl ete loss of intestinal motility associated with general anesthesia. Co nclusions-GLY significantly reduced the cardiovascular dysfunction att ributable to general anesthesia with XYL and KET. The return of intest inal motility was delayed by 3 to 6 hours without causing any serious side effects.