SHARK CARTILAGE (See Also Glycosaminoglycans) SHARK CARTILAGE (See Also Glycosaminoglycans)Common Use
Arthritis
There is reported a link between blood vessel growth and the development of osteoarthritis. In the synovial (joint) fluid of arthritic pets, there is an increasing amount of a chemical called endothelial cell-stimulating angiogenic factor. This chemical encourages growth of new blood vessels in the arthritic joint. It is theorized that by inhibiting angiogenesis (new blood vessel growth), further degeneration of cartilage might be prevented.
See glycosaminoglycans for a discussion of these kinds of agents in general.
In the laboratory, shark cartilage has been shown to contain chemicals that inhibit blood vessel formation. Because arthritis is an inflammatory condition, and inflammation requires blood vessels, it has been suggested that by inhibiting the formation of new blood vessels, shark cartilage can benefit arthritic pets. And in fact, research has shown this to be the case.
Shark cartilage has also been recommended for the treatment of cancerous tumors in people and pets. In fact, shark cartilage contains chemical compounds that prevent new blood vessel growth in test-tube experiments (a number of test-tube experiments have found that shark cartilage extracts prevent new blood vessels from forming in chick embryos and other test systems). Developing drugs to prevent blood vessels from forming in tumors is an exciting new approach to treating cancer.
In studies in both people and in dogs, significant improvement is seen in patients suffering from arthritis. Arthritic pets and people taking shark cartilage supplements often experience increased mobility and decreased pain. In one study, 8 of 10 dogs showed improvement (improvement was defined as no continuing lameness, lack of swelling and pain, and improved movement) when treated at a dosage of 750 mg/5 kg of body weight for 3 weeks. When treatment was temporarily discontinued, pain and lameness returned. Administering additional shark cartilage at 50% 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 the large amount of mucopolysaccharides (GAGs) contained in the cartilage, which can help nourish and heal the cartilage. As a result of studies such as this one, many veterinarians feel it is prudent to prescribe shark cartilage as it can be beneficial in some pets with arthritis and can substitute for therapy with medications like nonsteroidal drugs that have potential side effects.
The main problem with using shark cartilage to treat arthritis is the large dosage required. This suggested dosage would require giving a large number of capsules to the pet each day. And since shark cartilage 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.
There are several products on the market that supply a much lower dosage of shark cartilage than that listed in the studies reported to date. This lower dosage has proved beneficial in some arthritic dogs. Because shark cartilage is very expensive to use in larger dogs (approximately $40 to $50 for a 2-week supply), some owners are tempted to give less than the recommended dosage to decrease cost. This can be acceptable after a 1- to 2-month stabilization period. Work with your doctor to determine the most effective dose for your dog. 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.
Because cancers must create new blood vessels to feed them, shark cartilage has been touted as a cure for cancer. However, there is conflicting evidence as to its effectiveness. In several small but controversial studies, human patients with cancerous tumors did show regression (reduced size of the tumors). Other studies did not show any benefit. Because dogs and cats require a large dose to approximate the dose used in the human studies, this could be costly, especially for owners of larger dogs. Currently, most doctors do not use shark cartilage for the treatment of tumors in people or pets, as convincing research showing positive results is lacking. Additionally, factors such as the cost of the supplements, the potential for interference with proven cancer treatments, and the potentially devastating impacts on marine ecosystems have caused doctors to not routinely recommend this supplement for pets with cancer. While shark cartilage can be helpful for arthritic pets, the concerns mentioned above prompt doctors to recommend glucosamine and chondroitin supplements as their first choices for nutritional supplements.
Shark cartilage should not be used in people who have recently suffered a heart attack, in pregnant women, and those who have are recently recovering from deep surgery; similar precautions probably apply towards pets.
Because of conflicting evidence and the potential for impure product (quality control issues are important for all nutritional supplements), owners should consult with their doctors before using shark cartilage for any medical needs.