A Novel Formulation of Alfaxalone Increases the Utility for Remote Delivery in Bighorn Sheep (Ovis canadensis)
A combination of medetomidine, azaperone, and alfaxalone (MAA) has been used to induce reliable, reversible immobilization in wild ruminants.1 Alfaxalone is a GABAnergic neurosteroid which induces anesthesia with minimal cardiovascular side effects. It is currently commercially available in a 10 mg/mL concentration. This concentration restricts utility for wildlife capture of large ungulates due to volume limitations of remote delivery equipment. The objective of our study was to assess the impact of concentrated alfaxalone in MAA on induction and recovery time, using a new preserved formulation of alfaxalone (40 mg/mL) on a population of bighorn sheep (Ovis canadensis). Nine wild free-ranging bighorn sheep were injected intramuscularly with medetomidinea (0.15 mg/kg), azaperoneb (0.2 mg/kg), and alfaxalonec (1 mg/kg; 40 mg/mL) using remote delivery. The volume of alfaxalone ranged from 0.75 mL to 2.10 mL, with total drug volume administered in 1.5–3 mL darts depending on the mass of animal. Time to induction from dart delivery was 11:03±4:05 minutes. Once induced, deep sedation was maintained for 52:37±3:40 minutes. After biological and physiological sampling was performed, sedation was antagonized with atipamezoled (0.75 mg/kg) injected intramuscularly. Time from injection to standing was 3:49±1:49 minutes, with all sheep exhibiting slight to no ataxia and successfully ambulating on 60° slope. In prior studies approximately twice the drug volume was required, necessitating the use of 3–5 mL darts.2 We believe that the novel concentration (delivered in 1.5–3 mL darts) represents a significant refinement of this drug for use in remote delivery.
aMedetomidine 30 mg/mL, Bow Valley Research Inc., Calgary, Canada
bStresnil® 40 mg/mL, Elanco, Division Eli Lilly Canada Inc., Guelph, Canada
cAlfaxalone 40 mg/mL, Jurox Party Ltd, Rutherford, Australia
dAtipamezole 10 mg/mL, Bow Valley Research Inc., Calgary, Canada
The authors thank Sarah Hummel, Dr. Owen Slater, Erin Denny, Jenna Lambert, Alan Glassman, and Dr. Kirby Pasloske for assistance with animal handling, data collection, and technical support. This project was funded by the University of Calgary. Four percent (4%) Alfaxalone was graciously provided by Jurox Pty Ltd.
1. Mathieu A, Caulkett N, Stent PM, H Schwantje. Capture of free-ranging mule deer (Odocoileus hemionus) with a combination of medetomidine, azaperone and alfaxalone. J Wildl Dis. 2017;53:296–303.
2. Pon K, Caulkett N, Woodbury M. Efficacy and safety of a medetomidine-azaperone-alfaxalone combination in captive white-tailed deer (Odocoileus virginianus). J Zoo Wildl Med. 2016;47:29–37.