With a bear, an exit wound is a nice plus, as it will provide for a better blood trail, especially if the shot is not as good as one hoped for. Their loose skins, thick fur, and depending upon season or severity of winter and subsequent layer of fat, tends to make for poor blood trails. Keep in mind, that a hit high in the chest will allow the blood to pool within the chest cavity and not out into the ground, also making for a poorer blood trail. Try for a lower chest shot to prevent this. If the bear has more tissue damage to the lungs, the shorter the trail to the downed animal. (This is the same for all game animals)