Deep digital flexor (DDF) tendinitis refers to inflammation of the deep digital flexor tendon (DDFT) and is a specific type of tendon injury that occurs in horses. DDFT injuries can occur in the forelimbs and hindlimbs. Damage to specific areas of the DDFT are seen often in coorelation with the primary athletic activity of the horse. For example, forelimb DDFT injuries occur more often in the pastern region in endurance, polo, and barrel racing horses. DDF tendinitis occurs most frequently in the foot region of the forelimbs and hindlimbs of middle-aged performance horses.
The horse's deep digital flexor tendon (DDFT) provides support to the fetlock joint, acts as a spring that stores energy upon movement, and stabilizes the leg under full weight-bearing load. The DDFT is located just below the superficial digital flexor tendon (SDFT).
The DDFT runs along the back of the horse's leg, beginning just above the knee, passing through the tendon sheath at the back of the fetlock, widens and becomes flat, crosses the navicular bone, descends into the foot and attaches to the coffin bone, which is encased within the hoof wall.