I’ve got a dog and two cats. Both cats were a few years old before the pup came along. A couple of tips for you. Introduce the dog to the cat after you have exercised the dog well. Really let the dog get worn out so that once he is home he wants to sleep. This gives the cat and calm quiet dog to meet.
A dog with a high prey drive will make things difficult though not impossible. Don’t allow the dog to become excited around the cat. Given enough time, the cat will figure the dog out and develop ways to get around him.
Feed them at the same time. This is help to create a good feeling in both animals while they are together. Feed the cat up while the dog is fed down lower. This keeps the dog out of the cat food and avoid competition for food by the fastest eater.
Upon bring home the dog for the first time try to make sure that everyone smells like the cat. Scent is powerful with dogs and this may help to associate the cat with the pack.
Never forget that you are the leader and the dog must always be submissive to you and your family. Calm and submissive is the target.
Perhaps the most difficult part of bringing the dog home is keeping the excitement down.
Once the dog is a bit settled and relaxed, then you can reward the calm submissive behaviour with being excited. The best approach is to have your family members not look, talk or touch the dog until you are satisfied with the homecoming, show the dog around where the water and food is, the dogs bed and where to go to let you know it has to go out to take care of business.
Above all make sure the cat and the dog have plenty of ways to get around each other so they can choose to mingle on their own terms and in their own time. It will take time but if you remain calm around them both, and intervene if it gets rowdy they will at least abide each other and at best wind up best friends.
If you have heard of the Dog Whisperer, start watching the show and visit his website. Lots of great tips on getting the behaviour you want out of your dog.