A deer could suffer many types of death. Nature is not overly kind or compasionate. The majority of the deer I have taken had no idea of their fate and probably were more startled than in pain. Most of the gun kills dropped immediately and the majority of my bow kills seemed to react to the bow noise and then calm down before blacking out. I am a bit of a softy and pride myself on very humane harvests. The advice of lots of practice and smart shot placement will give you a high probability of a humane harvest if you choose to pursue game. Good luck.