Structure and Function of the Skeleton in Cats

Below is information about the structure and function of the feline skeleton. We will tell you about the general structure of the skeleton, how the skeleton works in cats, common diseases that affect the skeleton, and common diagnostic tests performed in cats to evaluate the skeleton.

What Is the Skeleton?

The skeleton is the bony framework of the body that is present in all vertebrate cats, dogs, and animals. 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). The cat skeleton has an average of 250 bones.

The cat’s skeletal design is very similar to ours, although there are two significant differences. First, a cat’s spine or backbone contains more bones that ours, mainly because of the tail. Their vertebrae are not as tightly connected as ours, making the cat’s spine extremely flexible. This feature enables the cat to arch his back and to twist or turn his body so that he can squeeze through the tiniest gaps. Second, the cat lacks a clavicle or collarbone. A collarbone would broaden the chest, thus reducing the cat’s ability to get through narrow spaces, and limiting the length of his stride.

Where Is the Skeleton Located?

The skeleton is located throughout the entire head and body of cats.

What Is the General Structure of the Feline 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 cats have the exact same size and shape to their bones. Since people have been breeding cats for thousands of years, bones may vary in their length and thickness depending on the specific breed.

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 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 Feline Skeleton?

The skeleton serves four functions:

What Are Some Diseases of a Cat’s Skeleton?

Congenital diseases. Certain congenital and developmental bone diseases occur in the cat, but are usually uncommon. Examples include the following:

Osteomyelitis. 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.

Nutritional disorders. Disorders that cause abnormalities in the circulating levels of calcium, phosphorous and certain vitamins can adversely affect bones. Examples include:

Trauma. Trauma to bones is perhaps the most common skeletal disorder encountered in the cat, especially outdoor cats. Cats that are injured through falls, automobile accidents and fights can experience a variety of bony fractures and dislocations.

Cancer. Neoplasia or cancer of bone is uncommon in the cat. Tumors may arise within the tissues of the bone or may invade bones from the surrounding soft tissues. Cats are most prone to cancers of the bone marrow, such as lymphosarcoma. Cancers of cortical and cancellous bone are more rare in the cat.

What Types of Diagnostic Tests Are Used to Evaluate the Skeleton?