How can I stop this behavior?

I had to laugh about having another animal. We have two crabby cats that are 13 and 14. Boy, do they ever hate the dog. lol It's been 7 months and they still can't walk past him without hissing at him. It does take his mind off of stealing the kids toys though. He loves those natural rib bones. I bought him one last night and he almost has it gone. I never knew how much money I'd be spending on bones when I got him. He has a few other bones that are pretty indestructible, but he keeps bringing them outside so we have to constantly go on a bone hunting party. Thanks for the advice!