This information came directly from Dr. Shawn Messonnier's book: 
"The Arthritis Solution for Dogs."

Bovine Cartilage:
Bovine cartilage is high in glycosaminoglycans that can help the body repair damaged joints. In dogs treated with bovine cartilage, good results were seen in the treatment of degenerative disk disease and some spinal disorders. The recommended dose of bovine cartilage is 200mgs per 25 pounds of body weight.  Perna Canaliculus: Perna canaliculus, the green lipped mussel, is a shellfish that is a natural source of highly concentrated glycosaminoglycans (GAGS) including chondroitin, complex proteins, amino acids, nucleic acids,
chelated minerals, and an inhibitor of prostaglandin synthesis that makes it effective as  an anti-inflammatory supplement. Glyco-Flex is one supplement made of perna mussels. 

Sea Cucumber:
The sea cucumber are marine animals related to urchins. They are believed to inhibit harmful prostaglandins involved in causing pain and arthritis. They are also rich in nutrients needed by cartilage, including chondroitin and mucopolysaccharides, and several vitamins and minerals. One product is the Sea Jerky treats made for dogs. The active ingredient was assumed to be chondroitin, but another substance called InflaStatin (now under research and development) is the active ingredient.

Shark Cartilage:
Researchers have reported a link between blood vessel growth and the development of arthritis. In the 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 new blood vessel growth, further degeneration of cartilage might be prevented. In the laboratory, shark cartilage has been shown to contain chemicals that inhibit blood vessel formation. The dosage is 750mgs per 5kgs body weight.

Glucosamine and Chondroitin Sulfate:
Glucosamine is an amino-sugar that is incorporated into joint cartilage. It is supplied as a supplement in one of
three forms: glucosamine sulfate, glucosamine hydrochloride, or N-acetylglucosamine. Studies show that while all three forms are effective, glucosamine HCL and glucosamine sulfate were more effective that N-acetylglucosamine. Glucosamine is rapidly taken up by cartilage cells and helps stimulate the synthesis of joint fluid and cartilage and also helps inhibit the destructive enzymes that 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. Dosages vary depending on the product. A guidline for combination gluc/chon products is a starting dose of 1,000 to 1,500 mgs of glucosamine with 800 to 1,200 mgs of chondroitin per day for a 50-100 pound dog. The dose is lowered
after 4-8 weeks.

DMG:
DMG is dimethylglycine. Research indicates that DMG reduces the incidence of arthritis and allows for the reversal of the inflammatory condition of some experimental animals with arthritis. Dosage is 50-250mgs per day.

MSM:
Methylsulfonylmethane is a natural anti-inflammatory and analgesic. It is a stable metabolite of DMSO. MSM supplies sulfur to the body, which can be used in the treatment of osteoarthritis. MSM is found naturally in meat, fish, eggs, poultry, milk, and other foods. MSM is very safe and may help treat arthritis via an anti-inflammatory benefit and providing sulfur used by the cartilage in the healing process.

Cetyl Myristoleate:
Cetyl myristoleate is an ester of a common fatty acid commonly found in fish oils, dairy butter, and animal fat. It isn't clear how CM works, but it may act similarly to omega-3 fatty acids. Veterinarians using a product called Myristin in combination with Myristaid, which contains glucosamine, MSM, and other herbs and antioxidants, have reported success in dogs with osteoarthritis.