It's really quite simple. The man is a hunter, his dog is a hunting dog. Where are you getting this "pub" scene? None of the lyrics of the version I know sound like anything of the sort. The bloke sounds quite content with his life. I must admit I have never heard the Pogues version, but, thats the beauty of the folk process. If a bluegrass band can get away with driving the piss out of "Make me a pallet" I guess one could make a dirge out of Jock Stewart.