Deep digital flexor tendinitis

Veterinary advice should be sought before applying any treatment or vaccine.

Deep Digital Flexor Tendinitis

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).
Deep digital flexor tendinitis
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.


Mild to moderate, intermittent or transient lameness
Heat, swelling and pain on palpation


  • History
  • Clinical signs
  • Physical exam
  • Ultrasound
  • Radiographs
  • MRI


Extended stall rest with controlled exercise
Cold therapy
Wrapping legs
Hyaluronic acid and polysulfated glycosaminoglycan injections


  • Increasing workload gradually rather than abruptly.
  • Regularly scheduling shoeings to avoid long toe, low heel configuration
  • Early recognition and treatment of other lameness to prevent compensatory tendon overload


Guarded to poor to return to previous performance

Scientific Research References

Good Overviews

Risk Factors

  • Overweight horses: Overweight horses place increased load on their tendons
  • Poor ground surface: Working horses on extremely hard or soft, uneven, slippery, or shifty ground surface
  • Muscle fatigue: Horses which are overworked alter their stride characteristics which change the distribution of forces placed on the tendons.
  • Contralateral limb lameness: Horses which are hurting in another leg will try to compensate by placing more load on the alternate leg.