Honestly it sounds like a dog who is unsure of what his role is supposed to be in his new home. Since no one else is volunteering for the role, he is trying to take the alpha spot in the pack. You need to correct him when he goes into aggressive mode to snap him out of it and to entrench your role as the leader. Get him when he is "stalking" with a sharp noise and a touch to the side if you are close enough. When he jumps on your older terrier, correct him, roll him belly up and hold him there for a minute or two until he stops struggling. He needs to learn that there are leaders in the house and his place in the pecking order is a little further down than what he aspires to be. |