I've seen deer in Minnesota make it through a winter on 3 legs after having there leg blew off half way down from gun hunters. As you all know winters in Minnesota can be some of the toughest around. If he looks healthy i wouldn't bother with it, if he isn't healthy i would shoot him. I've taken bucks, doe's, fawn's through out the year's that have been wounded during the gun season with my bow because i didn't think they would make it through the winter.