Are you being assertive enough in telling him no? Simply put, he’s doing it because he’s getting away with it. Dogs are pretty simple creatures in terms of how they respect others, you have to be the pack leader to have their respect. I have no doubt Cesar Millan would have some advice for you, perhaps consulting his show or books is advisable.
You can use a commercially available product called “Bitter Apple” or another called “Yuck Gel”. Make sure that he has plenty of chew-appropriate toys, and if all else fails, crate him when he’s not supervised.
@reijinni – He can’t spend a lot of time outside as he hasn’t had his shots yet, and he’s too small to go unsupervised. And no one has time to be outside with a dog all day long. As I’m sure you know, puppies will chew all day long.
@JellyB – I would not be lonely without the puppy. Then the Horus cat would probably hang out with me again. He’s currently not speaking to me, which makes me very sad.
@JellyB – Certainly. I miss him terribly. He won’t even come into the room until I clean it all up because it smells of dog. And he hates dogs, even small ones that are good for hunting (his hunting, you know).