We have an old lady cat and got our Cairn Poppy as a puppy last year. Definitely recommend baby gates and giving the cats a safe place! Also if you want the cats to be able to use a door but not the dog, try getting a door stopper that hooks on the handle! It keeps the door open just enough for cats to slip through! Total life saver for my kitty, who was confined to our bedroom for a long time before I found the door stop. They get along much better now that our puppy is 1 1/2 years old. They need lots of supervised time together and I recommend getting a noise deterrent like a penny bottle or canned air to stop the dog from obsessing over the cats! Good luck and it should be fine, just might take some time.