As dogs age, all the activities they engage in during their lives slowly begin to take their toll on the body. A dog who can run and play for hours in her youth may not be able to do so for quite as long or quite as rigorously a few years later.
Among other things, this is related to her body’s decreased stamina, which is affected by factors such as her bone and joint health. As dogs run and play, they begin to feel tired and exhausted, partly because of the stress placed on the skeletal system.
These stresses, part of the normal wear and tear of a dog’s life, can accumulate and begin to damage the skeletal system, particularly in the joints. The body’s natural compound for caring for and repairing joints, glucosamine, begins to gradually disappear from the body as the dog ages.
This is why joints feel stiffer and why dogs are not as flexible as they grow older. Consistent levels of glucosamine during the dog’s early and middle life are important to maintaining joint health and keeping your dog from experiencing the pain of arthritis as she ages.
Not all injuries a dog sustains in her first years of life are visible injuries, or even injuries that she can feel. A small injury to the cartilage in your dog’s knee or hip may not even slow her down. The cartilage that forms a cushion between the bones of the joints in your dog’s body is there to absorb shock and force that your dog encounters every day. Every time she runs, your dog’s cartilage sustains many tiny injuries that are naturally repaired when she rests or sleeps.
Glucosamine is present in your dog’s body naturally. It is a compound that is integral in making synovial fluid, which lubricates and nourishes joints, and in rebuilding cartilage, the cushions in joints that absorb the shock and wear and tear of daily living. Repeated stresses like those of normal playtime stimulate glucosamine production because of the multitude of small injuries to the tissues in the joints.
However, as your dog ages, she loses the ability to produce glucosamine. As she loses glucosamine, her joints lose the ability to repair themselves as well as they once did. Most dogs sustain a major injury during their lifetimes; large dogs in particular often injure their knees or hips.
One or two such injuries can often deplete your dog’s store of glucosamine significantly, and following such an injury she may experience stiffness or pain in the injured joint even long after it heals. As the cartilage loses its ability to repair itself, it begins to lose its elasticity and toughness, which are responsible for the durability and resilience of cartilaginous tissue.
Cartilage tissue in previously-injured areas may begin to degrade and lose mass. As cartilage disappears, so does the cushion between your dog’s joints. You may notice your dog limping at times, or you may see that she cannot play for periods of time as long as she used to.
These injuries that dogs sustain in their younger and middle years are what lead to the stiffness and limited mobility they experience in their later years. Senior dogs in particular have lost much of their natural supplies of glucosamine by the time they reach an advanced age. When glucosamine levels are depleted, the synovial membrane does not produce synovial fluid as readily.
Synovial fluid is responsible for much of cartilaginous tissues’ healing abilities, since it provides nutrients that allow cartilage to repair itself, as well as lubrication that prevents cartilage erosion in the first place.
When cartilage tissue does begin to erode, as it does naturally as a result of aging, the bones that form joints begin to produce friction by rubbing against each other in areas where the cartilage cushion between the bones is thinnest; in some places, cartilage may be completely gone. Bones are not meant to rub against each other in this way, and have only a very thin membrane of protective tissue surrounding them.
When the end of a bone, called a caput, rubs against the caput of another bone, the sustained friction of everyday movement can be very painful. When joint tissues deteriorate to this level, pieces of bone and cartilage can fragment off and remain in the joint space.
When this occurs, these loose bodies can become lodged in the articulating points of the joint, or the location where the bones meet and pivot off of each other to produce movement. This can cause added acute pain and may cause the joint to lock. Loose bodies may also cause your dog to fall down, her joints appearing to simply give way under her.
Depending on what your dog is doing when this happens, it can cause a joint injury that may be more difficult to recover from, owing to decreased efficacy of joint tissue healing. Bone spurs are also a common effect of arthritis. This is when the friction between bone ends stimulates osteocytes, or bone cells, to deposit bone matter, resulting in a pointed growth of bone tissues. When bone spurs occur, they can lead to pain in the area as well as numbness and increased difficulty walking.
The chronic issues that may occur as a result of normal wear and tear of joints and bones are not readily apparent. Chronic issues rarely cause immediately noticeable problems, instead causing a gradual decrease in function, such as a more limited range of motion or increased pain following rigorous exercise. You may not notice something is wrong with your dog’s joints until she has problems following a joint injury, such as an abnormally long recovery time or impaired function following healing.
Although these are normal effects of aging, they are not desirable, particularly when they cause a previously active and playful dog to develop a change in behavior as a reaction to chronic pain. In addition to the pain the animal feels, the owner must watch his pet live with chronic pain issues. Since glucosamine therapy has both preventative and reparative effects, a dog owner may wish to ask his dog’s veterinarian about the use of glucosamine to promote his dog’s continued joint health.