Last year I had two dogs start walking through my set up. They were headed into the area from which most of "my" deer would come. I put a bullet about a foot in front of the lead dog and they very quickly exited the way they came. I reasoned that I have had deer walk in to my set up just 10-15 minutes after killing one of their sisters. I don't believe a gun shot ruins the hunt, but I suspect that dead dog scent does.