Blood pressure responses to captive bolt and electrical stunning in sheep and cattle:A systematic review.

Electrical and captive bolt stunning rapidly increase blood pressure, potentially preserving consciousness.

This systematic review examines blood pressure responses following captive bolt and electrical stunning in cattle and sheep used for slaughter. The analysis of published literature reveals that both stunning methods consistently produce rapid increases in systemic arterial blood pressure within seconds of application, except when halothane anesthesia was used concurrently. Since cerebral perfusion depends primarily on systemic arterial blood pressure, the hypertensive response following these stunning techniques may paradoxically preserve brain viability. The physiological mechanism underlying this hypertensive response involves stimulation of excitatory centers in the upper brainstem and damage to inhibitory neurons that normally regulate brainstem and diencephalic excitatory centers. The elevated blood pressure following stunning may explain why some animals regain consciousness after initial unconsciousness, representing a significant animal welfare concern. The findings indicate that practitioners should be aware of this blood pressure elevation phenomenon when using electrical or captive bolt stunning methods, as maintaining elevated cerebral perfusion may inadvertently facilitate resumption of consciousness in stunned animals.

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