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Arthritis, or more correctly, osteoarthritis or degenerative joint disease (DJD), is a common condition in dogs and a rare condition in cats. Arthritis technically means "inflammation of the joint." Inflammation is characterized by swelling, stiffness, and pain; therapy is designed to counteract these effects of inflammation. When possible, the therapy should also slow down the progression of the arthritis, or, actually help the joint to heal.

A joint is the space between two bones. In dogs, the joints commonly affected with arthritis include the knee, shoulder, ankle, elbow, and most commonly, the hips. The joints between the vertebrae of the backbone also commonly develop arthritis. In cats, the backbone, hips, knees, and joints connecting the smaller bones of the feet are often afflicted.

As the animal walks and plays, a large amount of stress is placed on all the components of the joint. Biomechanical and biochemical alterations in the joint occur. With years of wear and tear on the joints, the cartilage breaks down and arthritis can develop. As wear and tear continues, the cartilage is disrupted and joint instability results.

The earlier the pet is diagnosed, the greater the chance for healing to occur using natural treatments.

Glucosamine For Pets

Glucosamine and chondroitin are commonly prescribed chondroprotective nutraceuticals. (See Totalhealth article on "Chondroitin for Osteoarthritis," in the Pet section, for more information on chondroitin.)

When we talk about chondroprotective nutraceuticals (nutritional products), we’re talking about "cartilage-protective" compounds. Unlike corticosteroids and other medications, these products actually help the cartilage rebuild and repair itself. In essence, they are "cartilage-friendly" products. These compounds also help relieve pain and inflammation. Interestingly, these improvements seem to last for several weeks after glucosamine supplements are discontinued. Chondroprotective agents can be given orally or by injection; often both forms will be used in the severely arthritic and painful pet.

Optimum functioning of the joints is important for pain-free movements by the pet. While any pet can exhibit lameness or arthritis, it is usually the older pet that is affected. Articular cartilage, the cartilage that lines the joints, must remain healthy to allow the pet to function at its maximum capability. The articular cartilage acts as a shock absorber for the joint, providing a smooth surface between bones to eliminate bone-on-bone contact. As the cartilage is destroyed, bony surfaces contact and irritate each other, causing pain, inflammation, and reduced activity. While corticosteroids and certain non-steroidal medications certainly relieve the pain and inflammation, they further destroy the articular cartilage making a bad situation even worse.

Cartilage is made of cells called chondrocytes that make a matrix of molecules, which add to the strength of the cartilage. This matrix consists of collagen, a protein that connects tissues, and substances called proteoglycans. These proteoglycans are made of glycosaminoglycans (GAGs) and hyaluronic acid. Surrounding the cartilage, and bathing the joint, is joint (synovial) fluid. Cartilage is a tough material that protects the underlying bones and acts as a shock absorber for the joints during movement.

There is a normal amount of wear and tear on the joint cartilage. The various cells and fluids are constantly being broken down and synthesized. It is important that the cartilage receive proper nutrition, especially when it is damaged and inflamed. Chondroprotective agents seek to replenish the raw materials that are essential for the healing and synthesis of cartilage, its matrix, and joint fluid.

Various products, each supplying different nutritional products, are available to assist in relieving inflammation and helping cartilage to heal when it is damaged. The following ingredients may be included in the various nutritional chondroprotective products. Each doctor has a "favorite" product. If one doesn’t help your pet, your doctor may suggest trying a different one. Keep in mind these are true holistic products; there are no harmful side effects such as those often encountered with the long-term use of corticosteroids or nonsteroidal medications.

Glucosamine is the most common chondroprotective supplement for the treatment of osteoarthritis. Glucosamine is produced naturally in the body, where it is a key building block for making cartilage. (It serves as a building block for the glycosaminoglycans and proteoglycans.) Glucosamine is an amino-sugar (made from glutamine and glucose) that is incorporated into the articular (joint) cartilage. It is supplied as a supplement in one of three forms: glucosamine sulfate, glucosamine hydrochloride (a salt of D-glucosamine; D-glucosamine is eventually converted by the body into glucosamine sulfate), or N-acetylglucosamine. Glucosamine is not usually obtained directly from food; supplements are derived from chitin, a substance found in the shells of shrimp, lobsters, and crabs.

Scientific Evidence
Studies show that while all three forms of glucosamine are effective, glucosamine hydrochloride and glucosamine sulfate were more effective than N-acetylglucosamine. Results take four to eight weeks to develop. Interestingly, these improvements often last for several weeks after glucosamine supplements are discontinued.

Glucosamine is rapidly taken up by cartilage cells and helps stimulate the synthesis of synovial fluid and cartilage, and also helps inhibit the destructive enzymes that can destroy cartilage and proteoglycans. The anti-inflammatory aspect of glucosamine may result from the scavenging of harmful free radicals (similar to antioxidants). Glucosamine is used by the cartilage for the synthesis of glycosaminoglycans.

A number of studies in people and pets show that glucosamine is equally effective for treating osteoarthritis when compared to NSAIDs, without the side effects. In fact, glucosamine and chondroitin are among the few supplements for which we actually have good studies in people and pets. For both people and pets, solid evidence indicates that glucosamine supplements effectively relieve pain and other symptoms of osteoarthritis. In both people and dogs, patients given glucosamine experienced significantly reduced pain and improved movement, to a greater extent than the improvements seen in the placebo groups.

Other studies showed that non-steroidal medications and glucosamine proved equally effective at reducing symptoms. In people, one group that received a combination treatment (nonsteroidal piroxicam plus glucosamine) didn't show significantly better results than either treatment taken alone. In this same study, after 90 days into the study, treatment was stopped and the participants were followed for an additional 60 days. The benefits of piroxicam rapidly disappeared, but the benefits of glucosamine lasted for the full 60 days.

While there are a number of glucosamine products from reputable manufacturers, many of the early major studies done in pets have used a proprietary product (Cosequin and Cosequin-DS) containing glucosamine and chondroitin. Clinical evidence indicates other products from well-known manufacturers are also effective.

Dosages vary depending upon the product. As a guideline for combination products, a starting dose of 1000 to 1500 mg of glucosamine with 800 to 1200 mg of chondroitin is recommended per day for a 50 to 100-pound dog. This dose is then lowered after four to eight weeks.

While arthritis is rare in cats when compared with dogs, clinical experience suggests that glucosamine and chondroitin products may also be quite helpful for arthritic cats. In general, the recommended dosage for smaller dogs is used.

Glucosamine appears to be extremely safe with no side effects; mild GI upset is rarely observed. No significant side effects have been reported in any of the studies of glucosamine.

Look for part 2 in the November issue of TotalHealth.

Shawn Messonnier, DVM

As my thank you for reading my articles, enter code “drshawn” at my natural products web store,, to save 10% on all your future purchases!

Shawn Messonnier DVM Past Supporting Member, Oncology Association of Naturopathic Physicians Author, the award-winning The Natural Health Bible for Dogs & Cats, The Natural Vet’s Guide to Preventing and Treating Cancer in Dogs, and Breast Choices for the Best Chances: Your Breasts, Your Life, and How YOU Can Win The Battle!

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