Exsanguination

Exsanguination is the process of blood loss, to a degree sufficient to cause death. One does not have to lose all of one's blood to cause death. Depending upon the age, health, and fitness level of the individual, people can die from losing half or two-thirds of their blood; a loss of roughly one-third of the blood volume is considered very serious. Even a single deep cut can warrant suturing and hospitalization, especially if trauma, a vein or artery, or another comorbidity is involved. It is most commonly known as "bleeding to death" or colloquially as "bleeding out". The word itself originated from Latin: ex ("out of") and sanguis ("blood").

Exsanguination is used as a method of slaughter. Before the fatal incision is made, the animal may be rendered insensible to pain by various methods, including captive bolt, electricity or chemical. Without prior sedation, stunning or anesthetic, this method of slaughter is understood by some to cause a high degree of anxiety, although other studies contradict these findings. The captive bolt is placed against the skull of the animal, and penetrates to cause tissue destruction in the brain, incapacitating the animal so that the procedure may take place. Electricity is used mostly in porcine, poultry and domestic sheep, whereas chemical is used in injured .

Continued pumping operation of the heart during exsanguination increases the rate of depletion, and thus hastens death, by raising the fluid pressure of the blood. Because the heart operates like a positive displacement pump, reduction of blood volume will not affect efficiency of cardiac output — deprivation of blood to the heart does gradually result in diminished function, but concurrently with similar death of other parts in the body.

...
Wikipedia