Immobilization of Black Bears (Ursus americanus) with a Combination of Butorphanol, Azaperone, and Medetomidine

Abstract

Sixteen captive and five free-ranging black bears (Ursus americanus) were immobilized with a combination of butorphanol, azaperone, and medetomidine (BAM). The BAM drug combination was premixed using 0.5 ml butorphanol (30 mg/ml), 0.25 ml azaperone (50 mg/ml), and 0.25 ml medetomidine (20 mg/ml) per milliliter to yield a final mix of (15 mg butorphanol+12.5 mg azaperone+5 mg medetomidine)/ml. This combination, dosed at 0.4 ml BAM/approximately 23 kg estimated body weight, provided a mean induction time of 10 min (95% confidence interval [CI]=2 min), consistent anesthesia without apparent adverse effects, and smooth recovery (mean=15 min, 95% CI=4 min) after antagonism with atipamezole (5 mg/mg medetomidine) alone or in combination with naltrexone (5 mg/mg butorphanol). Based on our initial observations, BAM appears to be a reversible and accessible drug combination for immobilizing black bears that merits further evaluation for field use.