Two Kinds of Stunning Most animals in Britain are stunned. An animal that is dead before it has bled out will be unsuitable for marketing. The latter definition regards stunning as rendering an animal unconscious, and the exsanguination as the cause of death. The author of this entry gives paralysis as an alternative to loss of consciousness. The captive bolt may penetrate the skull and destroy brain tissue, or cause a considerable rise in intracranial pressure.
Instant unconsciousness occurs if the aim is accurate, the animal is still, and the device works.
Electrical stunning involves passing a large voltage across the animal's brain. Slaughtermen, butchers, the Royal Society for the Prevention of Cruelty to Animals, the People's Dispensary for Sick Animals, Compassion in World Farming and most people who eat meat, assume that the electric current causes instantaneous unconsciousness, so that the animals feel no pain. Unfortunately, there is evidence that this assumption may not be warranted. Electric stimulation of the skin with low voltages and currents causes a tingling sensation, while higher power causes pain and burns, due to action on the sensory nerve endings in the skin. Stimulation of motor nerves or of muscle directly with low voltages and currents, causes muscles to contract, while higher powers causes spasm and paralysis.