The smallest dog breed is the chihuahua, which weighs 2-6 lbs (1-3kg) and stands 6-9in (15-23 cm) at the shoulder. However, the smallest fully-grown dog ever is in dispute: it is between two Yorkshire terriers, one named Whitney. They are both the same size, but Whitney was measured in 2002, making the other dog the current smallest dog. Which one do you think deserves the title?