I'm so sorry to hear about your parents dog. I agree with previous posts in that you are probably dealing with a pits animal aggression plus a stong prey drive, throw the fact that you've got puppies in and you've got a nightmare on your hands. I would recommend not allowing anyone unknown unsupervised near the pups/parents until the pups are found new homes. I'd definately keep any animals and children completely away as long as the pups are there. When there are pups involved even the gentlest dogs can be aggressive if they think the pups are in danger. I'd definately stick with your original plan to neuter him and probably spay the female if you can. Even if he's neutered he may be more aggressive when she's in heat. As posted previously make sure he knows your the boss, NILIF is a great starting point that doesn't cost any $$ to do. If possible ask your vet for the name of a good behaviourist/trainer in your area that handles dog aggression. They can evaluate your dog and give you some ideas based on your dogs personality. I agree one on one training is good to establish basic and teach him whose boss, but since he's animal aggressive I don't agree that, that should be the only training which is why I'm not sure Petsmart is your best option. The trainer I took Hunter to had 6 one on one sessions, plus they have group refresher courses once a month for as long as you want. They can not only socialize, but work on the skills they learned at the one on one in a social setting. If at all possible I'd work on getting him neutered and into training soon before the problems get worse.