Field Immobilization of Feral ‘Judas’ Donkeys (Equus Asinus) by Remote Injection of Medetomidine and Ketamine and Antagonism With Atipamezole

Abstract

ABSTRACT:The Judas technique is a method used for landscape control of feral donkeys (Equus asinus) in northern Australia. Central to the success of any Judas program is the safe, efficient, and humane attachment of the telemetry device. For feral donkeys, this involves the use of field immobilization. We examine the replacement of the current chemical capture agent, succinylcholine, with contemporary immobilization agents to achieve positive animal welfare outcomes. A combination of medetomidine and ketamine delivered by remote injection from a helicopter was used to capture 14 free-ranging feral donkeys for the fitting of telemetry collars in Western Australia in November 2010. Dose rates of 0.14 mg/kg medetomidine and 4.1 mg/kg ketamine were appropriate to immobilize animals in 9 min (6SD53). Mean recovery time (total time in recumbency) was 21 min (614). All animals recovered uneventfully after being administered atipamezole, a specific antagonist of medetomidine, intramuscularly at 0.35 mg/kg. Physiologic parameters were recorded during recumbency, with environment-related hyperthermia being the only abnormality recognized. No significant complications were encountered, and this drug combination represents an efficient approach to capturing wild donkeys. This new method allows a rapid, safe, cost-effective approach to the immobilization of feral donkeys for use as Judas animals. This drug combination will replace the relatively inhumane succinylcholine for the field immobilization of feral donkeys.

Assessing the efficacy of medetomidine and tiletamine–zolazepam for remote immobilisation of feral horses (Equus caballus)

“…The overall recumbency time produced by this combination was longer than for many similar studies (e.g. Woolnough et al 2012;Boardman et al 2014). …”

“…The dose of medetomidine used in the current study was higher than the dose used in a previous study on use in Przewalski's horses (0.07-0.10 mg kg -1 ; Matthews et al 1995), and slightly higher than that used to immobilise feral donkeys (0.14 mg kg -1 ; Woolnough et al 2012). Other studies have shown that comparable doses of medetomidine to those used in the current study have been administered to large ungulates previously without lethal side effects (Tyler et al 1990;Haulena et al 2000;Woolnough et al 2012;Boardman et al in press).…”

“…Other studies have shown that comparable doses of medetomidine to those used in the current study have been administered to large ungulates previously without lethal side effects (Tyler et al 1990;Haulena et al 2000;Woolnough et al 2012;Boardman et al in press). …”

“…In particular, the potent α-2 adrenergic agonist medetomidine, in combination with the cyclohexamine ketamine, has demonstrated reliable and reversible remote immobilisation of a diverse range of ungulate species, including forest reindeer (Rangifer tarandus fennicus; Jalanka 1989), ibex (Capra i. ibex; Jalanka and Roeken 1990), Przewalski's horse (Equus ferus przewalskii; Matthews et al 1995), donkeys (Equus asinus; Woolnough et al 2012) and dromedary camels (Camelus dromedarius; Boardman et al in press). The anaesthetic effects of medetomidine can be reversed, or antagonised, by the α-2 adrenergic antagonist atipamezole, with the effects of cyclohexamines dissipating over time (Woolnough et al 2012).…”

“…Despite its high potency and availability of an antagonist that enables rapid and complete reversal, etorphine is restricted for use in many countries, including Australia, and difficult to import (Woolnough et al 2012;Australian Government, Department of Health and Aging, 2013).…”