During the stunning of cattle, the objective is to damage the Ascending Reticular Activating System (ARAS). To assess the animal‘s state of unconsciousness, the absence of signs of risk of consciousness is assessed. These signs are controlled by structures near the ARAS. The rationale is that when the ARAS is damaged, these nearby structures are also affected. These links were confirmed by neuroanatomical analyses in the present study: the presence of signs of risk of consciousness post-stunning indicates a higher probability that the ARAS has not been damaged. The study also shows that when the ARAS is not damaged by the captive bolt pistol, in only a minority of cases the shot causes haemorrhages that induce unconsciousness. It is therefore essential to position the stun gun such that it maximises the probability of damaging the ARAS.
The study further confirms that post-stunning movements are not reliable indicators of the animal's state of consciousness.