Injuries to the superficial digital flexor tendon account for as much as 30% of all Thoroughbred racing injuries, and of those that do heal there is a high incidence of reoccurrence, according to Linda Dahlgren, DVM, PhD, Dipl. ACVS, of Virginia-Maryland Regional College of Veterinary Medicine. During the 51st Annual American Association of Equine Practitioners Convention, held in Seattle, Wash., Dec. 3-7, 2005, Dahlgren discussed of what’s new on the market for treating tendon and ligament injuries in horses.

Traditional tendonitis (tendon damage due to trauma) treatments include both medical and surgical approaches aimed at decreasing inflammation, preventing further damage within the tendon, releasing the strain on the injured tendon, and increasing blood flow with in the tendon lesion. The diagnostics of tendon injuries has increased greatly with the widespread availability of portable high-definition ultrasound machines. However, there has been little advancement in the treatment of these injuries that has significantly improved the chances of horses returning to full athletic soundness and/or decreased the risk of a reoccurrence of the injury.

“Tendons are composed of large amounts of extra cellular matrix (ECM) surrounding a relatively small number of highly differentiated fibroblast (a connective tissue cell),” Dahlgren said. Tendons heal by the formation of scar tissue. This tissue is mechanically and biochemically inferior to normal tissue.

“We really have a significant problem in resolving tendon injuries,” Dahlgren said. “The tendon is usually slow to heal. When it does heal, we are getting mostly scar tissue and there is reduced elasticity