My 13-month old male golden has been biting and bruising my wife for the last 8 months. Until 3 months ago, he still took direction from me and saw me as Alpha. Then one day, I put him into the car and he went into a vicious tirade and put a "kill bite" (as opposed to the usual Golden "soft bite") on my arm. He began snapping at small neighbor children 6 months ago. Then a few weeks ago, he tried to maul my adult son, jumping frantically at his arms and face, snapping his jaws, rapidly twisting his body and leaving strings of bubbly saliva everywhere. He has taken to tearing into me like this now, and rarely follows my direction. We have been working with a behaviorist/trainer, but he's actually becoming more vicisous. His last bite at me came through my glove and broke skin. Today at the dog park, a senior golden came up to sniff, and my dog jumped him and mauled him, biting his ear. He was ferocious, deep, loud growling with jaws continually snapping, foaming mouth, etc. He also got on top of the old dog, wrapped his legs around the dog's body and continually snapped into his neck and ears with strong bites. There seems to be a switch in his head that flips, and he turns into a dangerous monster. I have never witnessed a more vicious dog in my 50+ years, and I am moving in my mind towards either putting him in a no-kill shelter, giving him back to the breeder (who says that if he cant be placed, then she'll put him down) or even something more ultimate. It's just not fair and ethical to the people who live around us or the other dogs he meets. I am really torn about this, and am wondering if anybody else has seen this type of extreme behavior. If you have anything to share, I'm all ears.