Serum Enzimatic Changes in Halothane Anesthetized Athletic Horses

Abstract

Six horses (5 male, 1 female), 2 to 5 years of age, andweighing 430 to 510 kg, from the Brazilian Jockey Club(Rio de Janeiro, Brazil) were anaesthetised to performelective arthroscopic surgery during 1 :30 hr. Ali the animaiswere examined before the anaesthetic procedure. Foodbut not water was withheld from these horses for 12 hr.Xylazine (O. 75 mg/kg IV bwt) was administered as apreanaesthetic medication. Ketamine (2.2 mg/kg IV bwt)followed by rapid IV infusion of a 5% solution ofguaiphenesin (1 00 mg/kg bwt) were used to inducedanesthesia. The horse's trachea was intubated and theanimais were positioned in right lateral recumbency on apadded cart. The endotracheal tube was connected to asemi-closed rebreathing circuit system that delivered ahalothane-oxygen mixture. The facial artery wascannulated percutaneously for direct blood pressuremeasurement and connected to anaeroid manometer.Blood was collected from the jugular vein for biochemicalanalysis before anaesthesia (hour O, baseline) and 1, 2,8, 24, and 48 hr post anaesthetic induction. The enzymescreatine kinase (CK) and isoenzymes (CK-MB, Ci<-MM),aspartate transaminase (AST) and lactate dehydrogenase(LDH) were analyzed. No signs of post-anaestheticcomplications were observed in the immediate postoperativeperiod. In conclusion our data support that inshort procedures, there are enzymatic changes evenwithout clinicai signs of myopathy.