I'm sure I'll get flak for saying this, but given your unnerving description about the owners, perhaps think about getting a *** and learning how to use it, and not just against dogs.
It may not be practical, depending on the law where the OP lives. Also, that dog owner is probably armed and will return fire without hesitating. Not that you'd be wrong to shoot an attacking dog, but it may get a lot more ugly, fast.