I took Kelly to the vet yesterday because she occasionally hops on three legs and is not as active as she used to be. As it turned out, she has a mild degree of medial patella luxation, which is a common disease effecting small Maltese breed dogs. The vet said surgery is not recommended yet, but if she could lose a pound or two it would help very much to reduce the stress on her knee. My poor baby, but she loves to eat! We are going to try short and more frequent walks around the neighborhood and smaller portion of food. Hope this works!