My (soon to be) 5 month old Pem, Dexter, is becoming more and more aggressive. I believe it is because of his teething, but I can't be sure. I know his teeth are really bothering him, they are falling out and growing in, and he sometimes bleeds. I feel terrible about his pain, but the way he has been acting is unacceptable. He has a Nylabone, Kong, etc. I freeze rags and give them to him, and he loves pieces of ice. I feel like I'm doing the right thing for his teeth, so could it be something else? He gets exercise, but not as much as I'd like. We don't have a fenced in yard at this point, so we have to go outside and walk around the block. Maybe I'm just not forceful enough in training him. He never listens to our "No!'s" and is alllllwaaayyys biting both my husband and myself. I'm guessing it's due to his teeth, but again, not acceptable. He's very vocal, which can be funny, but not when he's ALWAYS growling or barking for attention. We play with him often, but the times that we aren't, he feels like we should be, and let's us know. 

Bottom line, Dexter thinks he's the boss, and I don't know how to fix this. I don't want him to grow up this way, so any help would be appreciated. Thank you!