Serum Enzimatic Changes in Halothane Anesthetized Athletic Horses

Abstract

Six horses (5 male, 1 female), 2 to 5 years of age, and weighing 430 to 510 kg, from the Brazilian Jockey Club (Rio de Janeiro, Brazil) were anaesthetised to perform elective arthroscopic surgery during 1 :30 hr. Ali the animais were examined before the anaesthetic procedure. Food but not water was withheld from these horses for 12 hr. Xylazine (O. 75 mg/kg IV bwt) was administered as a preanaesthetic medication. Ketamine (2.2 mg/kg IV bwt) followed by rapid IV infusion of a 5% solution of guaiphenesin (1 00 mg/kg bwt) were used to induced anesthesia. The horse's trachea was intubated and the animais were positioned in right lateral recumbency on a padded cart. The endotracheal tube was connected to a semi-closed rebreathing circuit system that delivered a halothane-oxygen mixture. The facial artery was cannulated percutaneously for direct blood pressure measurement and connected to anaeroid manometer. Blood was collected from the jugular vein for biochemical analysis before anaesthesia (hour O, baseline) and 1, 2, 8, 24, and 48 hr post anaesthetic induction. The enzymes creatine kinase (CK) and isoenzymes (CK-MB, Ci<-MM), aspartate transaminase (AST) and lactate dehydrogenase (LDH) were analyzed. No signs of post-anaesthetic complications were observed in the immediate postoperative period. In conclusion our data support that in short procedures, there are enzymatic changes even without clinicai signs of myopathy.