True. We were adopted by a cat a couple of years ago. That spring, this cat that looked to be maybe 9 or 10 months old started showing up all the time on our deck. After a month or so, and after we'd found her sleeping out there overnight a few times, we decided to start letting her in and feeding her regularly. Ultimately, we got her checked out at the vet, and got her vaccines and whatnot taken care of. So, yeah, I suppose you could say she owns us.
TNP has owned a dog that would jump to catch frisbees.