My experiences w/ heart shots mirror the ones already related-just amazing. I've read that deer have significantly fewer nerve endings than we do & therefore experience pain very differently. Just look at the life they live where injury or death is a daily reality even beyond hunting season whether through autos/trucks or predation, starvation,etc. If a deer were to break a leg, there is no 6-8 week recovery time, they must keep going or perish.
It is their will to survive, like all wild creatures, which keeps them fighting to the very end and leaves me in awe.