When I was a kid we had a German Shepherd and a Siamese cat that were the best of friends. They played like 2 puppies. Our cat would let our dog drag it around the house by it's head. The cat's entire head was in the dog's mouth. One time a lady was over visiting my Mom, for Avon or something - not an acquaintance. They were sitting in the kitchen and the dog came through dragging the cat by the head. The woman jumped up and screamed "That dog killed your cat!".
We had 2 rats when our kids were in grade school, Honey and Yogurt. They were the nicest rodent pets we've had. They're intelligent, clean, and they don't run away like hamsters and guinea pigs. If you can get past the freaky tail, they are really great pets.