The theory behind the reported effectiveness of glucosamine supplementation for dogs and cats suffering from osteoarthritis, often simply referred to with the broad term arthritis, is that glucosamine serves as a precursor to glycosaminoglycan. Glycosaminoglycan is utilized by cartilage building cells in the body called chondrocytes, to build and repair cartilaginous tissues in the body. Normally the body would produce glycosaminoglycan from glucose, so the glucosamine molecule is believed to provide additional molecular raw material to produce more glycosaminoglycan which in turn will enhance the function of chondrocytes to repair cartilage.
While studies have to date been conflicting on the efficacy of this process via oral glucosamine therapy, from an anecdotal standpoint, the veterinary medical establishment has appreciated overall improvement in osteoarthritis cases in dogs, cats, and horses. It is believed that two factors may affect the variability of study outcomes for oral glucosamine: the form of glucosamine in a given product (glucosamine sulfate is believed to be the most effective in conversion to glycosaminoglycan) and glucosamine being lost in digestion.
A pharmaceutical company called Novardis several years ago (the exact year escapes me), released a product called Adequan that contains pure injectable glycosaminoglycan. The injection could be given intramuscularly for cases of diffuse generalized arthritis in dogs, cats, and horses, or directly into a joint. The positive results in arthritis patients across species were irrefutable and it remains a very effective modality for management of arthritis in veterinary medicine today. What’s more, Adequan is now labelled for subcutaneous (under the skin) injection, which is less painful than in the muscle. There are also now several effective generic injectable glycosaminoglycan products on the market.
If my pet is getting glycosaminoglycan injections should I not bother with a glucosamine supplement?
My opinion on this is that the arthritic pet best benefits from the administration of both. From a comprehensive therapeutic point of view, the most reputable veterinary grade joint supplements have several other beneficial joint healthy elements in them such as omega-3-fatty acids, MSM, and chondroitin.
From a molecular perspective, the benefit of glucosamine extends beyond just glycosaminoglycan synthesis, but also proteoglycan synthesis. Proteoglycans are instrumental in collagen synthesis in the body, which is integral in the repair of the body’s connective tissues.
From an anecdotal case perspective, I have witnessed patients time and again (my own pets included) enjoy greater symptomatic relief and slowing of the progression of arthritis utilizing both injectable glycosaminoglycan injections and joint chews together than using either alone.
Dr. Roger Welton is the President of Maybeck Animal Hospital in West Melbourne, FL, Chief Editor of the Veterinary Advice and Information Website, Web-DVM, and founder/CEO of Dr. Roger’s Holistic Veterinary Care.