Hyaluronic acid (HA), also known as hyaluronan or hyaluronate, is a naturally occurring, non-sulfated, non-protein glycosaminoglycan (GAG) which is found in many parts of a human and animal body including joints (synovial fluid, cartilage), skin, eyes, brain, blood vessels, heart, etc. but more abundantly in articular cartilage and synovial fluid (Gupta 2019). HA can be produced from animal tissues such as rooster combs or via microbial fermentation.
HA’s function in joint health is related to its presentation in synovial fluid and the cartilage extracellular matrix, its unique rheological properties, and its biological activities.
HA is a high molecular weight (MW) polysaccharide composed of repeating polymeric disaccharides of D-glucuronic acid and N-acetyl-D-glucosamine. It has a high viscosity in water due to its high MW ranging from several hundred to several millions. HA has excellent viscoelasticity, high moisture retention capacity, high biocompatibility, and hygroscopic properties. By having these properties, HA acts as a lubricant, shock absorber, joint structure stabilizer, and water balance- and ﬂow resistance-regulator within cartilage and synovial fluid which is a thick liquid on all of joints including knees, shoulders, hips, etc. that lubricates joints and keeps them moving smoothly (Gupta 2019).
In addition to its rheological properties, HA has been reported with anti-oxidant, anti-inflammatory and analgesic effects and chondroprotective, anti-chondroptotic and cartilage repair effects (Gupta 2019). Studies found the functions of HA in joint health include preventing cartilage denaturation, protecting the outer layer of cartilage, blocking synovial inflammation, increasing chondrocyte density, promoting synovium metabolism, normalizing synovial fluid, and treating sharp pain (OE 2016).
When aging or with joint conditions such as osteoarthritis (OA), the levels of the HA or its molecular weight reduced in the joints (Gupta 2019). To restore the decreased levels of HA, intra-articular injection (IA) and supplementation of HA have been used in humans and animals.
HA has been used for more than 4 decades for joint health in dogs, horses and humans (Gupta 2019). IA injection of HA is reported to be clinically effective in alleviating articular pain and can slow the degeneration of articular cartilage in dogs (Gupta 2019, Carapeba 2016, Franklin 2013). Oral supplementation of HA alone or in combination with nutraceuticals (e.g. glucosamine, chondroitin, collagen, etc.) or NSAIDs (Nonsteroidal Anti-Inflammatory Drugs) has also been found to be beneficial for the prevention and treatment of OA in dogs (Marti-Angulo 2014, Alves 2017, Lv 2019).
There are debates if the high MW HA can be absorbed through oral supplementation. Balogh (2008) using rat and dog models demonstrated that oral administration of high MW HA was absorbed and distributed in animal tissues including joints, skin and bones. This finding supports the reports of biological actions seen after oral administration of high MW HA in animals.
1. Alves JC, Santos AM & Jorge PI (2017). Effect of an oral joint supplement when compared to carprofen in the management of hip osteoarthritis in working dogs. Top Companion Anim Med 32(4):126-129.
2. Balogh L, Polyak A, Mathe D, Kiraly R, Thuroczy J, Terez M, Janoki G, Ting Y, Bucci LR & Schauss AG (2008). Absorption, uptake and tissue affinity of high-molecular-weight Hsaluronan after oral administration in rats and dogs. J. Agric. Food Chem. 56: 10582-10593.
3. Carapeba GOL, Cavaleti P, Nicacio GM, Brinholi RB, Giuffrida R & Cassu RN (2016): Intra-articular Hyaluronic acid compared to traditional conservative treatment in dogs with osteoarthritis associated with hip dysplasia. Evidence-Based Complementary & Alternative Medicine 2016:2076921. doi: 10.1155/2016/2076921.
4. Franklin SP & Cook JL (2013): Prospective trial of autologous conditioned plasma versus hyaluronan plus corticosteroid for elbow osteoarthritis in dogs. Can. Vet. J. 54: 881-884.
5. Gupta RC, Lall R, Srivastava A & Sinha A (2019): Hyaluronic acid: Molecular mechanisms and therapeutic trajectory. Frontier in Veterinary Science 6: 192. doi: 10.3389/fvets.2019.00192. eCollection 2019.
6. Lv L, Wang Y, Yan Z & Lou H (2019). Study on the effect of oral hyaluronic acid to improve hip arthritis for dogs (Data on file).
7. Marti-Angulo S, Garcia-Lopez N & Diaz-Ramos A (2014). Efficacy of an oral hyaluronate and collagen supplement as a preventive treatment of elbow dysplasia. J. Vet. Sci. 15(4): 569-574.
8. OE M, Tashiro T, Yoshida H, Nishiyama H, Masuda Y, Maruyama K, Koikeda T, Maruya R & Fukui N (2016). Oral hyaluronan relieves knee pain: a review. Nutrition Journal 15 (11): doi: 10.1186/s12937-016-0128-2.