section_path: Anatomy and physiology/Size and skeleton
section_name: Size and skeleton
paragraph_text: Size and skeleton
  
  Dogs are extremely variable in size, ranging from one of the largest breeds, the Great Dane, at 50 to 79 kg (110 to 174 lb) and 71 to 81 cm (28 to 32 in), to one of the smallest, the Chihuahua, at 0.5 to 3 kg (1.1 to 6.6 lb) and 13 to 20 cm (5.1 to 7.9 in). All healthy dogs, regardless of their size and type, have an identical skeletal structure with the exception of the number of bones in the tail, although there is significant skeletal variation between dogs of different types. The dog's skeleton is well adapted for running; the vertebrae on the neck and back have extensions for back muscles, consisting of epaxial muscles and hypaxial muscles, to connect to; the long ribs provide room for the heart and lungs; and the shoulders are unattached to the skeleton, allowing for flexibility.
  
  Compared to the dog's wolf-like ancestors, selective breeding since domestication has seen the dog's skeleton larger in size for larger types such as mastiffs and miniaturised for smaller types such as terriers; dwarfism has been selectively used for some types where short legs are advantageous, such as dachshunds and corgis. Most dogs naturally have 26 vertebrae in their tails, but some with naturally short tails have as few as three.
  
  The dog's skull has identical components regardless of breed type, but there is significant divergence in terms of skull shape between types. The three basic skull shapes are the elongated dolichocephalic type as seen in sighthounds, the intermediate mesocephalic or mesaticephalic type, and the very short and broad brachycephalic type exemplified by mastiff type skulls. The jaw contains around 42 teeth, and is designed for the consumption of flesh. Dogs use their carnassial teeth to cut food into bite-sized chunks, more especially meat.