Our dog was knocked into a tree on a walk a few weeks ago by a large lurcher type dog chasing after him. It really hurt him, and he was dazed for a few seconds. Unfortunately, he has now become wary of all large dogs, even ones he was friendly with before. He freezes and barks and sometimes growls as a large dog approaches. If they try to approach him, he will tear off at lightening speed with his tail tucked. It’s so sad to watch. I spent so much time socialising him with dogs when he was a puppy. He used to love all dogs, big and small. What can I do to boost his confidence?