Behavioural and electroencephalographic assessment of captive-bolt stunning in kangaroo pouch young

Abstract During commercial harvesting (shooting) of kangaroos, pouch young of shot females must be euthanased to prevent suffering. The current euthanasia method, manually applied concussive (or blunt force) trauma to the head, can be effective but is not always applied consistently and is often perceived by observers to be inhumane. The captive-bolt device (CBD), which fires a steel bolt that either penetrates or impacts the skull, could provide a more suitable alternative. We reviewed a range of potentially suitable CBDs and assessed the effectiveness of four types on live animals. Effectiveness of CBDs was determined by assessing behaviour, electroencephalogram (EEG) and evaluating brain and skull trauma post mortem. Pouch young were also euthanased using manual blunt force trauma for comparison. Shooting with a penetrating CBD produced brain activity that was inconsistent with consciousness in 100% (n = 20) of animals. Behavioural indicators of consciousness and normal-like EEG were not detected after shooting with the CBD and damage to the brain was extensive. Seven out of 29 (24%) joeys shot with a non-penetrating CBD were either still breathing (n = 1) or recovered breathing (n = 6) after shooting. All seven animals had no or only mild damage to the medulla. We conclude that a cartridge-powered, penetrating CBD and manual blunt force trauma can both achieve immediate unconsciousness in pouch young, but a second step to exsanguinate the animal must still be performed. Penetrating CBDs are preferred to manual blunt force trauma since they are more repeatable, less reliant upon operator skill and confidence and more likely to reduce animal (and observer) distress.