SEVOFLURANE AND OXYGEN ANESTHESIA FOLLOWING ADMINISTRATION OF ATROPINE XYLAZINE GUAIFENESIN THIOPENTAL IN SPONTANEOUSLY BREATHING HORSES

The effects of sevoflurane-oxygen anaesthesia at a light-surgical dept h on clinically important features were evaluated in spontanteously br eathing horses that received atropine, xylazine, and guaifenesin-thiop ental. Mean end-tidal concentrations of sevoflurane ranged from 1.6 to 2.3% during 90 min maintenance. Recovery from anaesthesia was extreme ly rapid and smooth. Heart rates did not significantly change after an aesthesia. Arrhythmia was not observed. Mean arterial pressure (mean /- SD) ranged from 86 +/- 17 to 98 +/- 5 mmHg during anaesthesia. Minu te ventilation was low due to decreased respiratory rates during anaes thesia. Changes in arterial blood gases and pH demonstrated respirator y acidosis during anaesthesia. Haematological findings revealed haemod ilution during anaesthesia. Serum potassium decreased slightly during anaesthesia, but other serum biochemical values did not significantly change for 7 days post-anaesthesia. These results suggest that sevoflu rane may be an effective inhalant anaesthetic which produces a rapid r ecovery from anaesthesia in horses.