Helicopter‐based immobilization of moose using butorphanol–azaperone–medetomidine

Abstract

Chemical immobilization is an important tool for the capture, study, and management of wildlife. Increased regulation of traditional opioids has necessitated a search for alternative drugs in wildlife capture. Butorphanol-azaperone-medetomidine (BAM) is one promising alternative that has been used in a range of taxa, though often on medium-size mammals using groundbased methods. We tested the efficacy of BAM via remote delivery from a helicopter in a wild population of moose (Alces alces shirasi) in northwestern Wyoming. In March 2020 and 2021, we immobilized male (n = 15) and female (n = 26) moose with butorphanol (0.20 mg/kg), azaperone (0.066 mg/kg), and medetomidine (0.079 mg/kg), with antagonists atipamezole (0.495-0.527 mg/kg) and naltrexone (0.124-0.151 mg/kg) to reverse immobilizations. Mean induction (x̄± SE; 9.2 ± 0.6 min) and mean recovery times (7.2 ± 0.5 min) were longer but still comparable to published instances of moose captured using traditional chemical immobilizers (carfentanil, etorphine, thiafentanil). All animals survived >60 days post-capture. Our findings add to a body of work demonstrating that BAM provides rapid inductions, reliable sedation, and quick reversals in a variety of taxa and by aerial remote delivery.

Butorphanol, Azaperone, and Medetomidine for Chemical Immobilization in Free-Ranging Shiras (Alces alces shirasi) Moose: Ground and Helicopter Darting in Wyoming, USA

“…This is consistent with previous observations that supplemental oxygen appears to counteract observed hypoxia with alpha-2 agonist and opioid combinations (Wolfe et al 2014; Lamglait et al 2021). Some researchers have reported that supplemental oxygen was not necessary with BAM use (Levine et al 2022); however, those authors considered an SpO 2 of <70% (or a “downward trend”) as their cutoff. We recommend that supplemental oxygen be provided for planned captures of moose immobilized with BAM to decrease the likelihood of potential adverse health outcomes.…”

“…Anecdotally, we believe terrain type and features may play a role in this variation. Other researchers have reported that moose routinely remained in sternal recumbency without assistance under the influence of BAM (Levine et al 2022). In either situation, researchers should be cognizant of recumbency and positioning in their capture procedures.…”