I've been reading this thread for a while, and my heart goes out to you for what I know had to have been a really hard decision to have to make. My tiny chihuahua cross (weighs 5lbs soaking wet) got badly attacked by our biggest dog Greta (125lbs) a few months ago. Peanut's eye was popped from the socket, and her jaw was dislocated, but she did recover. Peanut was the instigater in the whole attack, and I now keep her crated when I'm not there to watch.With Greta it was no doubt a corrective nip, but being huge, she doesn't realize her jaw size! Greta is elderly, and a gentle dog, whereas Arthur was already starting to have aggression problems. Sometimes no matter what we do, things can erupt so quickly. Hope things calm down in your home, and that Charlie heals from his wounds.