The cat we had when I was a girl, used to stand up and jiggle the doorknob when she wanted out or in. My SIL's German Sheppard could open the car door with his nose. It was a certain type handle. We left one of the child proof locks on the cabinet that had the dry cat food in it, so our 2 cats couldn't get into the food. One cat would sit there and pull at the door, thump, thump, until one of us got up and gave her some food. Animals sure do entertain us.