I agree with your thoughts on putting him down. I would never tolerate that kind of behaviour either and she wants to put him down, however she has 3 boys between 20 and 25 and they would never agree to that. I don't know much about the situation as she has only just told me but she is so fearful of him and he's aware of that. I predict this is going to end badly and someone is going to be seriously injured. I know he is 5 years old and needs constant training,however that will never happen. A sad situation indeed. I have owned dogs for 40 years and trained for 20 years. It makes me cross when people bring home a puppy they think is cute when they know nothing about the breed. It's hard to help people that don't want to put in the work and don't want to be helped.