GLUCOSAMINE AND CHONDROITIN constitute the major GAGs in the joint cartilage: glycosaminoglycans serve as major components of articular cartilage. Glycosaminoglycans function by decreasing the presence of harmful pro-inflammatory prostaglandins and other inflammatory enzymes that degrade the cartilage matrix. This results in reduced pain and inflammation, decreased enzymatic destruction of the cartilage, and stimulation of anabolic (cartilage-building) pathways. The GAGs also appear to increase the synthesis of proteoglycans, hyaluronic acid (which acts as a joint lubricant), and collagen.
One novel product called Adequan contains glycosaminoglycans extracted for bovine cartilage and is available in an injectable form. The recommended regimen is a series of eight injections, two each week for four weeks. If the pet has responded favorably during the 4-week trial, the pet is then given an injection as needed (usually one injection every one to 12 months). This injectable product can be used with oral chondroprotective supplements as well. The injectable product can be used to get a faster response than the oral supplements. Further injections are given as needed, or pets can be maintained on oral supplements according to the response seen and the convenience of the pet owner. This product has also shown effectiveness when flushed into joints during joint surgery, allowing faster and smoother recovery.
Side effects with GAGs are extremely rare but are reported to include a dose-dependent inhibition of blood clotting. Concerned owners may want to have their pets' doctors regularly monitor blood coagulation parameters and use homeopathic remedies to help increase blood-clotting factors.
The following points concerning chondroprotective therapy are important to maximize success when using these supplements:
Safety. They are extremely safe and equally effective when compared to NSAIDs.
Cost. This may be an issue for some pet owners. The typical daily cost of using a glucosamine-chondroitin supplement is approximately $1.50/day for a 50-pound dog. This cost can decrease as the dosage of the supplement is lowered to allow the owner to use the least amount to maintain pain relief. The comparable cost of the most popular NSAIDs is approximately $2 to $3 a day for a 50-pound dog making the supplements less expensive, equally effective, and without potentially serious side effects.
Early Diagnosis. Since these supplements work by acting on living cartilage cells, they are most effective when used early in the course of the disease. This requires adequate and early diagnosis.
Response Time. Because they are not drugs but nutritional supplements, the response may not be seen for four to eight weeks. During the four to eight weeks, an increased "induction" dose is used and then the dose is lowered as improvement is seen. Additional short-term therapy (with NSAIDs, acupuncture, or other therapy) can be used during the induction phase.
Effectiveness. The supplements can also be used effectively when no clinical signs are present but yet disease exists. In many practices, a number of dogs are diagnosed via screening radiographs with hip dysplasia and started on the supplements pending a decision on the owner's part for surgical correction or until clinical signs occur.
Product Purity. The purity of products is an important factor. There are many generic knock-off products that sell for much less than patented products produced by reputable manufacturers. Studies have been done showing the effectiveness of these compounds that have used pure grades of products. Products of lesser purity, while often costing less, may also be less effective. Unlike traditional drugs, these compounds are not regulated and labeling can be inaccurate or misleading; manufacturers are not required to analyze their products regarding purity, uniformity, or content. Purchase only quality products from reputable manufacturers as recommended by your doctor.
Recommended Reevaluation. Because the chondroprotective supplements are so effective after four to eight weeks in improving signs seen in arthritic pets, the diagnosis should be reevaluted after this period of time if improvement is not seen.
There is a reported link between blood vessel growth and the development of osteoarthritis as well. The synovial (joint) fluid of arthritic pets includes an increasing amount of a chemical called endothelial cell-stimulating angiogenic factor. This chemical encourages the growth of new blood vessels in the arthritic joint. It is theorized that by inhibiting angiogenesis, further degeneration of cartilage might be prevented.
In the laboratory, shark cartilage has been shown to contain chemicals that inhibit blood vessel formation. Arthritic pets and people taking shark cartilage supplements often experience increased mobility and decreased pain. In one study, eight of ten dogs showed improvement when treated at a dosage of 750 mg/5 kg of body weight for three weeks. When treatment was temporarily discontinued, pain and lameness returned. Administering additional shark cartilage at 50 percent of the original dose resulted in improvement. The relief from pain and inflammation was theorized to occur as a result of decreased blood vessel formation.
Improvement may also result from a relief from pain due to a large number of mucopolysaccharides contained in the cartilage, which can help nourish and heal the cartilage. As a result of studies such as this one, many vets feel it is prudent to prescribe shark cartilage as it can substitute for therapy with medications like non-steroidal drugs that have potential side effects. The main problem with using shark cartilage is the large dosage required. This suggested dosage would require giving a large number of capsules to the pet daily. And since it is among our more expensive supplements, the dosage of shark cartilage needed for medium to large breed arthritic dogs would be unaffordable for most pet owners.
Shark cartilage should not be used in people who have recently suffered a heart attack, in pregnant women, and those who have or are recently recovering from deep surgery. Similar precautions probably apply to pets.
Because of the potential for impure product, owners should consult with their doctors before using shark cartilage.
Several products on the market supply a much lower dosage than that listed in the reported studies. This lower dosage has proved beneficial in some dogs. Because shark cartilage is very expensive to use in larger dogs ($40 to $50 for 2-week supply) some owners are tempted to give less than the recommended dosage. This can be useful after a one to two month stabilization period. Work with your doctor to determine the most effective dose. As is often the case with nutritional supplements, we don't know the best or most effective dose for shark cartilage. Therefore, we must use the products currently available and adapt the dosage to the individual pet's needs.
Perna canaliculus, the green-lipped mussel, is a shellfish that is a natural source of highly concentrated glycosaminoglycans (GAGs), including chondroitin, as well as a number of other nutrients, including complex proteins, amino acids, nucleic acids, naturally chelated minerals, and an inhibitor of prostaglandin syntheses, which makes it effective as an anti-inflammatory supplement.
Several studies in people have confirmed improvement in patients with osteoarthritis and rheumatoid arthritis. Ongoing studies, as well as anecdotal evidence, show the benefit of Perna in dogs with osteoarthritis. (Benefits in cats are scant, as arthritis is quite rare in cats when compared to dogs. However, veterinarians are using many dog products safely in cats.)
Stabilized powder (Seatone, MacFarlane Laboratories, Surrey Hills, Victoria, Australia) and the lipid extract (Lyprinol, MacFarlane Laboratories, Surrey Hills, Victoria, Australia) showed similar results in people with rheumatoid and osteoarthritis. The lipid extract is a 20-fold concentrate of the originally dried mussel. As is true with the powder form, the lipid extract is believed to be a potent but slow-acting antiinflammatory that inhibits cyclooxygenase and5-lipooxygenase. This is probably via the omega-3 fatty acid content of the mussels. In a laboratory experiment in rats, the dosage of Lyprinol was 20 mg/kg. In studies in people, a dosage of 300 mg twice daily for the first 30 days followed by a dosage of 150 mg twice daily showed positive results. Check with your vet for dog and cat dosages of these products.
Perna is inexpensive and readily accepted by most dogs. A product showing favorable results in pets is called Glyco-Flex Plus; it combines benefits of Perna with MSM.
The sea cucumber, cucumaria frondosa, also known by the names, trepang and beche demer, is a marine animal related to urchins. It is believed these organisms inhibit harmful prostaglandins involved in causing pain and arthritis. They are also rich in nutrients needed by cartilage. One popular product supplies the sea cucumber in a unique jerky-type treat (Sea Jerky-R), which dogs find quite palatable. Other compounds in this product include sea kelp, natural vitamin E, lecithin, garlic, omega-3, and glucosamine hydrochloride. Each treat provides 1200 mg of chondroitin.
In testing by independent laboratories the product showed excellent anti-inflammatory activity in rats. The anti-inflammatory response was superior to that of Rimadyl and phenylbutazone. This study also showed that Sea Jerky-R had higher activity than a product made from Perna mussels and a glucosamine/chondroitin supplement, indicating this product might be preferred if a dog fails to respond to another supplement.
The recommended dosage for this product is one piece of jerky per day for a 60 to 70-pound dog. While it was assumed the active ingredient in the product was chondroitin, further research showed that while the sea cucumber contains chondroitin, another substance called InflaStatin appears to be the active ingredient.
These treats are perfect for the dog that is hard to medicate.
The jerky treats can also be used in conjunction with other similar pill supplements, as it is unlikely to overdose a pet on glucosamine or chondroitin. For those pets with arthritis, most owners and doctors like the idea of giving them a daily treat that is good for them.