The really old timer, who I used to hunt Hogs with, would always walk up to a downed hog and poke them in the eye with his rifle barrel, loaded, safety off. My guess is he had been there done that.
I've had them look deader than heck and start kicking again. One even popped up and did a few rounds with my Dog before escaping into the thick brush.
Waidmannsheil, sounds like a fun and memorable hunt.