Anesthetic and cardiorespiratory effects of medetomidine, lidocaine, butorphanol and propofol total intravenous anesthesia (MLBP-TIVA) were evaluated in horses undergoing an experimental surgery. Ten horses were premedicated with an intravenous injection (IV) of medetomidine (5μg/kg) and butorphanol (20μg/kg). Anesthesia was induced by administration of 1% propofol (3mg/kg, IV) at a rate of 1 mg/kg/min (n=5, group-1) or 2% propofol administered at a rate of 6 mg/kg/min (n=5, group-2) following administration of lidocaine (1 mg/kg, IV) and then maintained by infusions of propofol, medetomidine (3.5μg/kg/hr), lidocaine (3mg/kg/hr) and butorphanol (24μg/kg/hr). The mean durations of anesthesia and propofol infusion rate required for maintaining surgical anesthesia were 130±17 min and 0.10±0.01mg/kg/min in group 1 and 129±14 min and 0.10±0.02 mg/kg/min in group 2. Four horses in group 1 and 2 horses in group 2 paddled following recumbency during induction of anesthesia. The median quality scores for induction (0-4: poor-excellent) and recovery (0-5: unable to stand-excellent) were 3 and 4 for both groups, respectively. Transition to anesthesia (the first 20-min period after induction) was uneventful in group 2, while all horses showed a light plane of anesthesia in group 1. The quality score (0-3: poor-excellent) for the transition to anesthesia in group 2 was significantly higher than in group 1 (median 3 versus 1, P=0.009). Heart rate and arterial blood pressure were maintained within acceptable ranges, but hypercapnia occurred during anesthesia in both groups. In conclusion, MLBP-TIVA may provide clinically useful surgical anesthesia in horses. A rapid induction with propofol may improve the qualities of induction and transition to MLBP-TIVA.
Anesthetic and Cardiorespiratory Effects of Propofol, Medetomidine, Lidocaine and Butorphanol Total Intravenous Anesthesia in Horses
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