EVALUATION OF SELECTED CARDIOPULMONARY AND CEREBRAL RESPONSES DURING MEDETOMIDINE, PROPOFOL, AND HALOTHANE ANESTHESIA FOR LAPAROSCOPY IN DOGS

Objectives-To compare the dose-sparing effect of medetomidine on the p ropofol induction dose and concentration of halothane for maintenance of anesthesia during laparoscopy and to provide guidelines for effecti ve and safe use of these anesthetics in dogs to ensure desirable perio perative analgesia. Animals-14 purpose-bred dogs. Procedure-Cardiopulm onary and electroencephalographic responses were determined during 2 a nesthesia protocols in dogs scheduled for laparoscopy. Fifteen minutes before anesthesia induction, ail dogs received atropine sulfate (0.02 mg/kg of body weight. IM). Seven dogs were then given propofol (6.6 m g/kg, IV); anesthesia was maintained with halothane in oxygen. The oth er dogs were given medetomidine hydrochloride (10 mu g/kg, IM) 5 minut es after administration of atropine sulfate, anesthesia was then induc ed by administration of propofol (2.8 mg/kg, IV) and was maintained wi th halothane in oxygen. Results-The halothane concentration required f or laparoscopy was lower in dogs given medetomidine. Anesthetic requir ements were significantly increased during abdominal manipulation in b oth groups. Total amplitude of the electroencephalograph in medetomidi ne-treated dogs was not significantly lower than that in dogs not give n medetomidine. Pulmonary responses were stable throughout all procedu res. The primary cardiovascular response was an increase in blood pres sure associated with the medetomidine-atropine preanesthetic combinati on. Significant differences in total amplitude or frequency shifts !sp ectral edge) of brain wave activity were not associated with surgical stimulation. Conclusion-Lack of neurologic changes during laparoscopy supports the efficacy of either medetomidine-propofol-halothane or pro pofol-halothane combinations at higher concentrations to provide desir able analgesia and anesthesia in this group of dogs.