There's no way I could get away with vigilante justice
This kinda stuff get's me excited for some reason. I had a neighbor with a problem dog. Before they moved I realized the worst thing I did was bring it to their attention, and the attention of the proper authority. After that, it was in my best interest to keep that dog alive, or else I'd be getting a knock at my door.
Most of the time it's the owner's fault and not the fault of the dog, but you get in less trouble for killing a dog I think.