Subclinical Synovitis

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Stiffness and lameness, clinical signs associated with osteoarthritis (OA),1 are all too common for performance horses. Synovitis, an inflammation of the joints, is one of the earliest changes in the joints of these athletic animals often related to repetitive trauma from training or performing. This could eventually lead to OA.1


But, the onset of synovitis may be occurring at a subclinical level--prior to horses showing signs.

“Performance horses are powerful athletes, but joint inflammation may lead to poor performance and potentially progress to OA,” said Hoyt Cheramie, DVM, MS, DACVS, manager, Merial Large Animal Veterinary Services. “That’s why early recognition of subclinical synovitis and intervention with LEGEND (hyaluronate sodium) is essential to prevent permanent joint damage.”

Since training can cause repetitive-use trauma to the joints leading to synovitis, consider treating performance-focused horses with LEGEND. With millions of doses sold and more than 20 years of treatment success, LEGEND remains an important drug of choice in the battle against equine non-infectious synovitis. By decreasing the production and release of the molecules that play a role in inflammation, LEGEND helps reduce joint inflammation and the resulting pain and lameness.2

How it Works
LEGEND is pure hyaluronic acid produced through a patented biofermentation process, and purified through a 12-step microfiltration process. This filtration removes impurities and foreign proteins that could cause adverse joint flares. Hyaluronic acid has been shown to stimulate synoviocytes to naturally produce more hyaluronic acid in the horse.3

LEGEND is the first FDA-approved intravenous (IV) joint therapy backed by decades of experience manufacturing hyaluronate sodium indicated for the treatment of joint dysfunction of the carpus or fetlock in horses due to non-infectious synovitis associated with equine OA. That’s a legacy you can have confidence in.

Merial is a world-leading, innovation-driven animal health company, providing a comprehensive range of products to enhance the health and well-being of a wide range of animals. Merial employs 6,100 people and operates in more than 150 countries worldwide with over €2 billion of sales in 2014. Merial is a Sanofi company. For more information, please see

1. Carmona JU, Prades M. Pathophysiology of osteoarthritis. Compendium Equine. 2009;4:28-40.
2. Kawcak, CE; Frisbie, DD; Trotter, GW; McIlwraith, CW; Gillette, SM; Powers, BE; Walton, RM: Effects of intravenous administration of sodium hyaluronate on carpal joints in exercising horses after arthroscopic surgery and osteochondral fragmentation. AJVR 1997; 58(10):1132-1140.
3. Smith MM, Ghosh P. The synthesis of hyaluronic acid by human synovial fibroblasts is influenced by the nature of the hyaluronate in the extracellular environment. Rheumatol Int. 1987;7(3):113-122.