Some third-hand physiology: Once an animal is wounded by the first shot, the effect of second and third shots is much less than that of the original. Thus, with dangerous game, cartridges/bullets which can break bone become far more important. Adrenalin has overcome the shock effect of the original, non-instantaneous-stop hit, and the only way to stop the animal is via the incapacitation of broken bones.
Now, all the above is from reading, okay? I guess I have some verification from stories of bad hits on whitetails, wherein there are parallels. All this is why I prefer to take a neck shot whenever possible. Nothing survives a broken spine.
Art