The skeletal system is the structural foundation for all vertebrates, including canines. It consists of bones, cartilage, ligaments and tendons. Bone is a versatile biomaterial that serves a multitude of functions – it serves as a storehouse for calcium, phosphorus and many other elements; a factory for red blood cells and for several kinds of white blood cells; supports and protects the body; act as levers for muscular action; acid-base balance, detoxification, and sound processing. In the normal adult dog, bone also stores fat.
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 breast bone (sternum). The visceral bones are the small bony parts of such organs as the inner ear. The long bones have growth plates that produce cartilage, which is converted to bone as the dog grows. At puberty, this bone growth slows, and the growth plates close when the dog reaches physical maturity, allowing no further growth.
A dog's skeleton has an average of 319 bones, which is about 100 more bones than humans. Dogs have the greatest variety in the size and configuration of their skeletons of any species of animal. 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. The biggest differences (other than sheer size) are in the bones of the skull. A dog’s shoulder blades are not tightly connected to its skeleton, so the dog has potential for greater motion and flexibility.
The skeletal system is a dynamic structure throughout a canine’s lifetime and is continuously remodeled. Specialized cells manage the remodeling process – osteoblasts promote bone formation, osteoclasts control bone resorption and chondrocytes maintain cartilage. Collectively, these processes preserve the structural integrity of a skeletal system.
In addition to providing structure, the canine skeletal system, particularly the bone, actually has multiple roles in the body. Below are eight of its vital functions:The Bone as a Mineral Bank
Bones serve as storage reserves (aka “bank”) for calcium, phosphorus and other essential nutrients. These nutrients are continuously deposited (bone formation via osteoblasts) and withdrawn (bone resorption via osteoclasts) from the bone to support vital body functions (such as maintain osmotic balance, fire nerve impulses, etc.).The Bone's Role in Blood Production
The bone marrow of long bones and the inner space of spongy bone produce blood cells via the hematopoiesis process; in other words, your dog’s bone marrow acts as a “blood factory”. The bone marrow is also the site where certain immune cells (B cells) are produced.The Bone Provides Protection
Bones protect vital organs. For example, your dog’s skull is like a helmet, protecting the sensitive brain from impact. Similarly, your dog’s rib cage shields the lungs, heart and liver from physical damage.The Bone Regulates Acid-Base (pH) Balance
For organs to function normally, your dog needs to maintain physiological pH. It is actually the bone in your dog’s skeletal system that works to buffer the blood (against extreme fluctuations in pH) by absorbing and releasing alkaline salts as needed.The Bone and Detoxification
Your dog’s bone tissues are involved in absorbing heavy metals and toxins. These resilient tissues remove undesirable compounds from the blood by forming complexes with them, and then disposing of them via the circulatory system – thus minimizing toxic side effects.The Bone and Sound Management
Sense of hearing is possible in part because of the auditory ossicles (“hearing bones”), three small bones that work collectively to transmit sound stimuli to receptor cells in the brain for interpretation. They help detect several aspects of sound such as pitch, loudness and direction.The Bone Enables Movement
Your dog’s bones, tendons, ligaments, and skeletal muscles work together to facilitate movement of individual body parts, as well as the whole body, whether it is for the purpose of catching a ball, going on a walk, or running to greet you at the door when you come home from work.The Bone Gives Structure
Bones provide the structural framework on which your dog’s body is built – they impart distinct shape (which we can use to identify similarities and differences between breeds) and also influence posture and gait.
This content is written by our Clinical Advisory Board for informational purposes only. It should not be viewed as an endorsement for any product or as a substitute for the advice of your veterinarian.