Cody is now 7.5 months old and is doing ok in most ways but we've still got one problem. When he gets excited he bites. i know there are many forums on here tackling this problem, but mainly in younger pups. Most of the time he is lovely but occasionally he starts to bite then it becomes more aggressive. Tonight it was my daughters birthday party and cody has been shut in the kitchen most of the night as I was too worried about him biting my daughters friends. Turned out that I was justified in this as during the evening when cody was chewing a chew my son went up to him and he bit him quite viciously, drawing blood. Then i took his chew into the kitchen to entice him in there and he turned aggressive with me, growling, baring his teeth and biting me, again drawing blood. whenever i went near to him he snapped at me or growled. Is this normal? How should I deal with it? We have tried ignoring him, shutting him in the kitchen, walking away from him, all of which work for a while then have no effect. Tonight i have been in tears. I love Cody but I'm worried about his aggression. Sometimes I've ignored him and allowed him to bite for so long and I'm wondering whether this has contributed to his behaviour. Also on occasions I have let play get a little rough. I'm worried that I've caused this behaviour and that it is irreversible. I know this is a long post but can anyone give me any advice?