Oh poor Purrley! When Trevor came to live with me 8 years ago there were two dogs in the house. At my first vet appointment with Trev the vet said "where are you keeping his litterbox because you know the dogs will very much enjoy the contents! GAG!" Although he had been kept in my son's room at the time with the door closed, we immediately went out and bought a pet door. It is a little flap that fits over a cut-out in the door that the cats can go through and it is on our basement door. Bella can only get her head in! HA! Since Tess is so small you might be able to use a puppy gate. That would have not worked for me because my dogs could scale puppy gates at an early age. If all else fails you might try the "secret cat flap" as it is known around here. Then again, at the size that Tess is, she could probably fit right through! If so, I guess the puppy gate is the better way to go. Cats can sail right over it and Tess won't be able to do anything but watch them!