Naki'o, a mixed-breed dog with four prosthetic devices, shows the mountain bike tire tread used for the bottom of his paw, in Colorado Springs April 12, 2013. Naki'o lost all four feet to frostbite when he was abandoned as a puppy in a foreclosed home. Picture taken April 12, 2013. REUTERS/Rick Wilking (UNITED STATES - Tags: SOCIETY ANIMALS HEALTH)