I've seen a cat that thinks it's a dog. It's quite odd. We were out walking one day and a cat darted past us, and stopped, and turned, the way dog's do when their owners aren't keeping up. Two other dogs caught up and they all stopped in a group, panting and wagging their tails. Apparently, the cat was an orphan and had been brought up with the puppies and for all intents and purposes thought it was a dog and behaved like one.