Hmm, I guess what I would do is get a kitten (or cat who doesn't have pre-existing 'dog hate') and teach Pepper to be very gentle with the cat. If she's never met one before you will probably have good luck teaching her to be good with cats. If you just want to find out how she is before hand, I would just ask someone who has cats if you can bring her over, or maybe take her to the shelter to meet a few.