Like all other skeletal animals, the dog's skeleton is made to protect vital inner organs, provide a stable base for the body, and allow it to move and perform various functions. The bones of the skeleton also provide essential nutrients and storage of vitamins and minerals for the body. The skeleton of a dog is basically the same as that of a giraffe, a horse, a mouse, and even a human. The differences lie in size, and form more than actual types of bones.
Dogs, like people, are members of the vertebrate family. This means their bodies are shaped by a skeleton and centred on a spinal column. The spinal column houses the central nervous system and is a primary key to every bodily function.
Number of bones
Dogs have 319 bones on average, with the difference being the possibility of bones being artificially removed with the removal of part of the tail (tail docking). Every dog has the same number of bones regardless of whether it is big or small. A Pomeranian is the same inside as a Great Dane. The differences are in size and length of the bones, not the number of bones.
The canine skeleton is comprised of three main areas: appendicular, axial, and visceral. The appendicular skeleton makes up the bones of the legs and feet, the axial portion of the skeleton is the main axis of support, the head, neck, spine, ribs, and beast bone (sternum). The visceral bones are the small bony parts of such organs as the inner ear.
Bones of all vertebrates are comprised of many layers of tissue. They are not a single solid piece of material like they may appear to be. They are comprised of the periosteum, a membrane that encases the bone; the cortical bone, the firm, thick, material that makes a bone strong; the cancellous bone, the interior part of the bone that is spongy and compartmentalised like a honeycomb. The cencellous portion of the bone actually gives the outer structure more strength. Bones contain marrow in the centre medullary cavity that is made up of fat, and in some bones (primarily the appendicular and axial bones) red and white blood cells.
The differences in bones between breeds are in size and shape. The biggest differences (other than sheer size) are in the bones of the skull.
Skeletal Tendencies for Hereditary Conditions
Some of the man-made size differences in breeds cause inherent difficulties that lead to illness. Many of the larger breeds of dogs have such weight placed on the skeletal capacity that it creates problems such as panosteitis, an inflammation of the long bones located in the marrow cavity. Hip dysplasia is another skeletal problem often occurring in large, heavy breeds, but also in dogs with very long backs.