Also to add to what I said there are certain dogs that have problems and should be put down to protect everyone, it sounds harsh, but there's a difference between a dog defending itself and attacking. Good example is on another fourm I'm on a girl showed us pictures of herself after a dog attack. Basically it was her friend's dog, it came up to her and rolled over on it's back and looked at her, as if to ask for a tummy rub, when she went to do so, killbite to her face. That's very different than a dog that was abused and is scared, this dog went into a submissive position that in dog language shows submission and trust, then attacked. Something is very wrong in a case like that and the dog could be mentally unstable, just as some humans are born with mental disorders there have been cases of animals with mental problems, these may not be fixable and in situations like that, the dog should be euthanized as hard as it is.