Below is information about the structure and function of the canine skeleton. We will tell you about the general structure of skeleton, how bones work in dogs, common diseases that affect the skeleton and common diagnostic tests performed in dogs to evaluate the skeleton.
What Is the Skeleton?
The skeleton is the bony framework of the body that is present in all vertebrate animals, including dogs. It consists of bones, ligaments, and cartilage. The skeleton is composed of the hard tissues of the body, and its primary functions are to support the body, to provide a system of levers used in locomotion, to protect the soft organs of the body, and to produce red blood cells (hematopoiesis).
A dog’s skeleton is formed so the dog can run fast, hunt and chase. For example, a dog’s shoulder blades are not tightly connected to its skeleton, so the dog has potential for greater motion and flexibility. The dog skeleton has an average of 319 bones.
Where Is the Skeleton Located in Dogs?
The skeleton is located throughout the entire head and body.
What Is the General Structure of the Canine Skeleton?
The skeleton is composed of three skeletal subunits:
Bones are organs composed of hard, mineralized tissue that provide structural support to the body. Not all dogs have the exact same size and shape to their bones. Since people have been breeding dogs for hundreds of years, bones vary greatly in their length and thickness depending on the specific breed. Even though the tiny Chihuahua has the same number and type of bones as the Great Dane, the size and shape of their bones are very different. Dogs have the greatest variety in the size and configuration of their skeletons of any species of animal.
The skeleton consists of bones that may be classified according to shape:
Bones contain several layers of tissue. The periosteum, a fibrous membrane, covers the outside of bone. This membrane is rich in small blood vessels called capillaries, which are responsible for nourishing bone.
The firm, dense, outer layer of bone is called cortical bone. Eighty percent of skeletal bone mass is cortical bone. Cortical bone assumes much of the weight bearing of the body. Cancellous bone (also called trabecular bone) is an inner spongy structure that resembles honeycomb. Cancellous bone accounts for 20 percent of bone mass. This spongy mesh-like bone is specially designed for strength, with the meshwork behaving similar to the steel rebar rods that are buried within concrete.
Bones also contain bone marrow within the hollow center shaft of bone (medullary cavity). Marrow is yellow when it is made up of mostly fat, and it is red in areas where red and white blood cells are produced. Red marrow is present in certain bones, like the leg (femur), upper arm (humerus), pelvis (ilium), and ribs.
What Are the Functions of the Skeleton in Dogs?
The skeleton serves four functions:
What Are Some Diseases of the Skeleton in Dogs?
Certain congenital and developmental bone diseases occur in the dog. Examples include the following:
Numerous other developmental abnormalities of joints may affect young dogs, such as aseptic necrosis of the head of the femur, dislocation of the knee cap (patella), and elbow dysplasia.
Osteomyelitis is an inflammation of bone that is usually caused by a bacterial infection. Infections of the bone may also arise with certain fungal infections and in the presence of bone implants, such as bone plates and pins.
Trauma. Trauma to bones is perhaps the most common skeletal disorder encountered in the dogs, especially dogs allowed to roam free. Dogs that are injured through falls, automobile accidents or fights can experience a variety of bony fractures and dislocations.
Cancer. Neoplasia or cancer of bone occurs in the dog. Tumors may arise within the tissues of the bone or may invade bones from the surrounding soft tissues. Large breed dogs develop more bone cancer than do small breed dogs. Dogs may also develop cancers of the bone marrow, such as lymphosarcoma.