As a dog lover, it's painful for me to say this, but some folks are getting dogs as weapons. At least that's what I'm seeing more and more of in my area. Should I honestly believe my life, or the life of a loved one, is in immediate danger, I would not hesitate to end the threat. However, I suspect several of the previous posters have hit on something worth trying. Get the bear spray and hope you won't have to use it, because you run of bad dog luck is over.