Your dog chases the cat around the house. In most cases, Fido doesn't really want to hurt Felix. It's the thrill of the chase that's fun - but it can be a real pain for the cat.
Mikkel Becker, pet trainer with Vetstreet.com says the solution is to prevent the cat from running in the first place.
"One of the best things you can do is give your cat a high space to go to," she explained. "If you have vertical spaces within your home, such as cat shelving or cat trees, somewhere where they can get up and away from the dog, that's really helpful."
You can also pull your furniture away from the wall a little bit. That way, the cat can easily go back there and retreat and the dog can't necessarily follow.
In some cases, you may want to keep the cat in a separate room.
You may also need to teach the dog to get along with the cat. Put your pooch on a leash when the two are together and reward calm behavior until Fido gets with the program.
Mikkel says unless you are absolutely sure the dog and cat get along together, it's best to keep them separated when you're not around. That way you can be sure there won't be any problems.
More info: Can I teach My Dog to Stop Chasing the Cat?