Duke the Cat was a highly aggressive and irritable cat that only appeared in "The Petriot Act". When he arrived, he turned out to be agressive when he hissed at Hank, Peggy, and Bobby and raced back into his kennel. Hank couldn't even board Duke up along with Ladybird. Duke is Dolan-like color, brown tabby cat & white. Duke made the Hill's vacation impossible and their life a living hell by vomiting on the table, scratching Hank's face and defecating in his shoes. Duke also dried up the vacation money as Hank was swayed to buy expensive cat food and tests by Dr. Leslie, Duke's vet. Even though Duke's tests were actually normal, Dr. Leslie exploited the situation more and more. After more expensive tests and buying Duke a wheelchair, Peggy suggested taking Duke to Dr.Yandell for a second opinion. Dr. Yandell respected Dr. Leslie, but claims Duke is normal and the tests only justify the price of expensive machines. Armed with a brochure on the machine, Hank blackmailed the vet into signing Duke's bill of health. With drained finances, the Hills settled for a rib joint, but they were finally happy to be rid of Duke once and for all.