Osteoarthritis in Dogs
Osteoarthritis is often described as "wear and tear" arthritis. Many cases of lameness, including osteoarthritis, can be traced back to stresses or injuries to a dog’s joints often caused by a traumatic event or other accident, although conditions like hip dysplasia will cause it as well. The “wear and tear” of aging, or the overwork of an animal given its physical condition, can also produce osteoarthritis.
Evidence suggests that the causes of osteoarthritis are not as simple as we would like to think they are because it frequently develops in many joints at the same time and often symmetrically develops on both sides of the body even when there is no reason to believe that equal amounts of “wear and tear” are present.
These factors, as well as others, have led to the suggestion that arthritis may actually be a body-wide disease of the cartilage.
Whatever the ultimate cause, the destructive and debilitating cycle of osteoarthritis usually involves an initial injury to the cartilage. The degraded cells that make up cartilage are then unable to synthesize enough of the proteoglycans, a major portion of the substance in the cartilage matrix, to help the cartilage heal itself.
Because the cells that make up the cartilage become degraded and don’t heal, destructive inflammatory enzymes are also released in the region of the affected joint, which in turn further act to damage the joint’s cartilage. These enzymes also start to break down the synovial joint fluid that functions as a lubricant and cushioning agent for the smooth movements of the joint.
As this destructive cycle continues, the progressive breakdown of cartilage and joint fluid in turn causes more irritation and further releases of destructive enzymes with subsequent increases in inflammation. As the destructive cycle continues, the result is pain, inflammation and joint instability
But that’s not all.
As the cartilage – the spongy, protective cushion between the bones in a joint -- wears away, the joint surfaces that are supposed to glide over each other smoothly become rough and as the lubrication within the joint decreases, the joint bones eventually start rubbing against one another. In time the bone beneath the cartilage starts to become damaged and wears away causing pain, inflammation and stiffness. A dog may then refuse to use the affected limb, which is when pet owners most often come to a vet seeking medical care and attention. Even massaging your dog to make them feel better won't work.
Thus, in osteoarthritis the cartilage first breaks down within a joint and then the ends of the bones in the joint space rub against one another causing deformity, pain, inflammation and stiffness. In canine arthritis, the cartilage that most commonly breaks down is in the hip, knee, elbow and ankle joints, but other joints can also be affected such as the joints between the vertebrae of the backbone.
For many pets, the end result means difficulty rising from a lying or sitting position, or limping or crying when a tender area is touched. This difficulty is most pronounced in the morning, after your dog has been sleeping and immobile for many hours. When we have full blown osteoarthritis it’s called “ degenerative joint disease” (DJD), which is when the degenerative changes in the bone can been seen in radiographs (X-rays). Sometimes an animal will develop canine hip dysplasia as well.
Osteoarthritis is one of the major reasons why your animals’ movements become more difficult and painful and yet the signs of osteoarthritis often escape many owners, who may believe that their pet is just “slowing up and getting older.” That reasoning, while seeming logical, often hides what’s really going on and gives owners an excuse not to take their dog to the vet when a trip can save the animal tremendous pain and suffering.
Some pets can be helped with nutritional therapies to heal their joints, whereas the condition may be so advanced in others that you can only work to slow the disease or mitigate the pain rather than effect true healing. The earlier a pet is brought to a veterinarian and diagnosed, the greater the chances for healing to occur using holistic veterinary therapies.
Dogs will often compensate for the pain they experience so we don’t notice it by adjusting their gait, balancing out their limbs with slower movements, and/or walking slower or just becoming less active to deal with the condition. The onset of osteoarthritis can be either acute or slow, but this “slowing up” of an animal is usually one of the major signs indicating the condition.
The proteoglycan molecule is composed of a central protein core with numerous side chain molecules called glycosaminoglycans (GAGS). Glucosamine is a precursor chemical necessary for the production of GAGS and chondroitin sulfate is just one of several different types of proteoglycan molecules found in joint cartilage.
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