Hi. Thanks for your replies. I do take my dog to dog obedience and have done since he was about 3 months old. I dont think my dog has a mental health problem. He reacts to a situation, which involves dogs and people approaching me. There is no doubt he is overly protective. He is very predictable. I can tell when he will swipe. When he bit the trainer (on the hand) it was in a context. And I knew it was coming. My dog DOESSS have behaviour problems, I admit that. I have been told dogs have a personality change at 8 and 12 months, so this coupled with training, a muzzle and a VERYYYY responsible dog owner, gives him good chance of change. If he does not change at training I will get 1:1 trainer for him. Please also acknowledge his intelligence, his age, he has learnt a lot. He has stopped biting my other dog, he stops barking when I tell him, he has started to walk past people quietly. I know I have a long way to go. I seek people's ideas about how to deal with aggression to other dogs especially. When he is in "a state" I yell "no", and make him "drop" and sit quietly. Any other ideas please?? I socialise him at shops and parks also.

Originally posted by carrie:
Hi,
This a major problem and it must be sorted! At six months old your dog is a baby and it will only get worse and he is only going to get bigger, more powerful and more dangerous.
Putting a muzzle on him is vital.
This is so important that you must seek a proffesional at once to help you. There is no ifs or buts and any modification you attempt on your own may make the situation worse. If you can't afford proffesional help then I'm afraid you can't keep the dog. A puppy showing this amount of aggression is going to grow into a very dangerous animal. Even with proffesional help you may have to accept that the dog has a mental health condition that can't be controlled. Do not put this off! Act now to save a lot of heartache and certain future injury to other people. I repeat a puppy of this age showing this amount of aggression needs to be asessed by a profesional a soon as possible.