Use of sevoflurane for anesthetic management of horses during thoracotomy

Objective-To evaluate sevoflurane as an inhalation anesthetic for thoracoto my in horses. Animals-18 horses between 2 and 15 years old. Procedure-4 horses were used to develop surgical techniques and were euthan atized at the end of the procedure. The remaining 14 horses were selected, because they had an episode of bleeding from their lungs during strenuous e xercise. General anesthesia was induced with xylazine (1.0 mg/kg of body we ight, IV) followed by ketamine (2.0 mg/kg, IV). Anesthesia was maintained w ith sevoflurane in oxygen delivered via a circle anesthetic breathing circu it. Ventilation was controlled to maintain PaCO2 at approximately 45 mm Hg. Neuromuscular blocking drugs (succinylcholine or atracurium) were administ ered to eliminate spontaneous breathing efforts and to facilitate surgery. Cardiovascular performance was monitored and supported as indicated. Results-2 of the 14 horses not euthanatized died as a result of ventricular fibrillation. Mean (+/- SD) duration of anesthesia was 304.9 +/- 64.1 minu tes for horses that survived and 216.7 +/- 85.5 minutes for horses that wer e euthanatized or died. Our subjective opinion was that sevoflurane afforde d good control of anesthetic depth during induction, maintenance, and recov ery. Conclusions and Clinical Relevance-Administration of sevoflurane together w ith neuromuscular blocking drugs provides stable and easily controllable an esthetic management of horses for elective thoracotomy and cardiac manipula tion.