Cats can make good friends for guinea pigs! I've tried putting one of my guinea pigs near my cat, but she just gets scared and runs away. But some cats would like a little piggie friend. Just be careful and always supervise your cat and guinea pig when there in the same room together! It's a good idea to put your cat on a leash and harness when there first meeting. That way if your cat tries to pounce or attack your piggie you can quickly pull the cat away. Make sure to be very careful when having your cat around your guinea pig! Because guinea pigs smell a lot like mice, so your cat's instinct might be to pounce! Here is a picture I found on google of a cat hanging out with a guinea pig:

                                                          Photo courtesy of Baby-Gaga.com