Polysulfated glycosaminoglycan (PSGAG), sold under the brand name Adequan, is an injectable drug for dogs and horses that is used to alleviate the limpness, pain, and lowered range of motion caused by arthritis.

[2] It is made of repeat disaccharide units (comprising hexosamine and hexuronic acid), and is similar to glycosaminoglycans already present in the cartilage; PSGAG thus easily integrates itself there.

[5] While it is widely used, some studies still show conflicting results in terms of efficacy, causing some to claim that PSGAG is not solely responsible for the significant mitigation of arthritis seen in success cases.

[4] In degenerative joint disease, the proteoglycan complexes start disappearing, and the hyaluronate becomes poorer in quality and scarcer.

This lowers the viscosity of the synovial fluid (which increases friction) and causes white blood cells and enzymes to enter and effect cartilage degradation and inflammation.

[6][10] The enzymes that are inhibited include serine proteases, which play a role in the IL-1 degradation of proteoglycans and collagen; lysosomal enzymes that cause proteoglycans to dissociate from hyaluronic acid; elastase; metalloproteinases such as stromelysin, which degrade cartilage matrix proteins; collagenases such as cathepsin B1; and hyaluronidase.

[4][12] PSGAG inhibits the synthesis of prostaglandin E2, which is released upon joint injury and causes inflammation, increases the loss of proteoglycan, and reduces the threshold of pain receptors.

The inhibition of blood coagulation reduces resultant fibrinolysis, which would cause cell death and increase local inflammation.