Agree, Pat Hastings is an excellent referance. One week Kohl was up on his toes, the next week flat as a pancake. It can be rather ugly. Age, hormonal changes, diet, level of exercise (make sure you're not crating too much) can contribuite to changes. He was put on Ester -C, 1000 mg. tab. He's also fed 1/2 Canidae, 1/2 raw diet with Solid Gold seameal/prozyme.