I'm with Cal on this one. The dog was probably pissed that the old man was scabbing his job of retrieving the bird!
Reminds me of an article I read many years ago of a man who was shot by his lawnmower! Someone had dropped a live round on the lawn and when he ran over it with the mower the primer was hit and he was shot in the lower leg. Sounds almost like a Monty Python skit! Try to imagine what was going through the minds of the cops at the E.R. when they had to write up the gunshot victim report.