I am an old dog person; Once bred, trained, worked, and showed Rotts in both AKC and German Klubs. They sell sound devices that affect dogs. The dogs reactions vary from running from the sound to a muting of the prey and territorial drive. The sound device will be effective on nearly all dogs. .....If you get a tone deaf dog, the reaction will vary. The sound device is a good first line defense. Pepper spay is a solid backup! If you are feeling angry and aggressive, or are an insecure fear biter, use pepper spay as the first defense. You are right! It is not the dogs fault. Renters are a problem, because they generally feel insecure and their dogs pick up on their emotions. Pepper spraying the owners would be more just, but.... you know....