In the Left 4 Dead (left4dead) and Left 4 Dead 2 (left4dead2 and left4dead2_dlc3) sound files, there are some sounds similiar to a dog. All of them seem to have been cut, but they still exist in the game files. The attack sounds for "zombiedog" were recycled for the Hunter when he'd attack with his claws. This could explain why the Hunter yelps like a dog when he is killed. According to some of the Church Guy's "combatcolor" sound files, the "dog" sounds seem to have been re-made for when he would turn into a Hunter.