Cat & Dog - Glycosaminoglycans (GAGs)

What are glycosaminoglycans?

Glycosaminoglycans (GAGs) are combinations of proteins and sugars and are found in a variety of tissues, including the blood plasma, joints, and the mucosal (mucous membrane) lining of a variety of organs, including the gastrointestinal tract, respiratory tract and the bladder.

Various GAG compounds exist. For example, glucosamine and chondroitin constitute the major GAGs in the joints of dogs while in cats, dermatan sulfate and heparin sulfate constitute the major GAGs coating the bladder wall. GAGs are among the most prescribed supplements in all of veterinary medicine.   See our handout on Glucosamine and chondroitin products.

Why recommend administration of GAGs to my pet?

Pets with arthritis are often treated with GAGs. GAGs can affect the major pathways involved in the breakdown of cartilage which occurs in arthritis by decreasing the production of harmful compounds, including prostaglandins. Like non steroidal anti-inflamatory drugs, this results in reduced pain and inflammation and permits cartilage synthesis to occur.

GAGs can also serve as the structural building blocks of this new joint cartilage, giving them a double benefit in the management of degenerative joint disease and osteoarthritis.

GAGs also appear to increase the synthesis of proteoglycans, hyaluronic acid (which acts as a joint lubricant) and collagen, all of which are needed for proper joint structure and function. GAGs are not effective in all animals, however, and may take 4 to 8 weeks to produce improvement in animals that do respond. While most studies of the benefits of GAGs utilise injectable preparations, oral supplements appear to be well absorbed.

Other emerging potential indications for glucosamine include the treatment of intervertebral disc (spinal) disease, recurrent cystitis (bladder inflammation), and severe inflammatory bowel disease.

Disc disease in the vertebral column of the back is associated with abnormal forces on discs, requiring their re-modeling and repair. Glucosamine has been suggested as a potential source of the proteoglycan molecules needed during this re-building processes.

Cats have been shown to experience a reduction with age in the GAG layer coating the urinary tract which may predispose to cystitis. Reduced levels of dermatan sulphate and heparin sulphate are also a feature of cats with feline lower urinary tract disease (FLUTD), suggesting that GAG supplementation may be of benefit in reducing inflammation and recurrence of cystitis. GAGs may also provide protection for the gastrointestinal mucosa in inflammatory bowel disease.

How much experience is there with the use of glycosaminoglycans in pets?

GAGs have been used for many years as a treatment for pets with arthritis. These products have a long track record of clinical safety.

What species of animals are being treated regularly with GAGs?

Dogs and horses are the main species treated with this supplement. Cats also benefit.

How much research has been conducted on this supplement?

GAGs have been shown to be effective in the management of degenerative and inflammatory joint disease as seen in arthritis. These research results are echoed by clinical experience, although not all animals will appear to respond. While glucosamine and chondroitin are available in oral forms, injectable forms are also available.

How safe are GAGs?

They are very safe, especially when compared to the potential side effects of treatment with NSAIDs (Metacam or Rimadyl for example). The only conceivable downside to their use is that they may not work. Side effects with the injected polysulphate GAG products are extremely rare but are reported to include inhibition of blood clotting.

It is recommended that we monitor your pet’s blood coagulation parameters on a regular basis if this is deemed to be a concern. Questions have also been raised about supplementation with GAGs in diabetic animals, since they are made from glucose (sugar). Current research shows, however, that glucosamine is safe to use in these animals, although it is still wise to monitor blood sugar levels in diabetic pets (especially if higher doses of glucosamine are used) as alterations in insulin levels might be needed, however that's rare.

Where do I obtain glycosaminoglycans and do I need a prescription?

Injectable products are administered by vets, sometimes with the patient under sedation (for joint injections) and require a prescription. Oral products do not require a prescription but may vary widely in content and quality.

At this practice, we use GAG products regularly for arthritis and for cystitis in cats. Please talk to one of the vets if you would like to discuss the use of this type of product with your pet.