HylaRx is an oral supplement containing Hyaluronan in a gel base for all horses. Hyaluronic acid, or Hyaluronan as it is currently called, role in joint function has been studied for more than half a century. Hyaluronan (HA) is a polyanionic nonsulfated glycosaminoglycan. It is part of the make-up of synovial fluid and articular cartilage in joints. HA is responsible for the viscosity and elasticity of synovial fluid. HA is thought to increase lubrication of soft tissue in the joint. HA may also stimulate high molecular weight production in the joint. The Horse Journal (May, 2002) cited positive results in the use of 100 mg per day of oral HA.