My daughter has a part chi-part yorki, we call her a Chorkie. She is six monhs old, and she never slows down until she is worn out. Then a nice nap and she is good to go again. She is the most loveable pup in the world, loves to jump to the back of the couch and lean around to give "kisses"galore. That little dog can jump from the floor over the arm of as chair to get to us.!! She is going to fixed soon , but I wonder if even that will slow her down. Our Shizu was fixed, she is three, and she is a bundle of energy still, especially when she gets with the Chorki.