The fetlock is a high-motion joint that undergoes significant compression and force absorption when the horse is moving. This joint is highly susceptible injury of both the soft tissues and bones associated with the region. [2]

Horses with fetlock injury often show signs of heat, pain, lameness, and swelling. In severe cases, horses may be unable to bear weight on the limb. [1]

Performance horses, such as racehorses and dressage horses, are prone to hind fetlock injuries. Eventers are more prone to fore-fetlock injuries, likely due to the landing forces after large jumps. [3]

Fetlock disorders range from minor issues requiring temporary rest and ice to career-ending injuries. [1] Vigilance and quick intervention are necessary to give your horse the best possible chance of recovery.

You can help to prevent fetlock injury in your horse with good care and management. Keep your horse at a healthy body weight, condition them appropriately for their job, and watch closely for any signs of soreness.

Always ensure that you support your horse’s joints with a good nutrition program and consider supplementing with anti-inflammatory nutrients that promote joint comfort.

Signs of Fetlock Lameness

The fetlock plays a critical role in supporting the horse’s weight. As a result, lameness can be seen even with minor injuries.

Injury is relatively easy to notice in this joint because the soft tissue structures of the fetlock have limited protective coverings (i.e. fascia and fatty tissue).

You can look for swelling or heat around the fetlock as one of the first signs of injury. Other signs of injury include: [1][6]

  • Edema, or swelling in the soft tissue structures around the joint
  • Effusion, or swelling within the joint capsule
  • Reluctance to bear weight on the affected limb
  • Reduced range of motion in the fetlock
  • Pain on palpation
  • Lameness, such as a shortened stride in the affected limb
  • A “dropping” of one or both fetlocks that is lower than normal

Diagnosis

To diagnose fetlock injury in your horse, your veterinarian will performa a musculoskeletal exam. Palpation of the area will identify any heat, pain, or swelling. Additionally, passive flexion of the limb will help assess range of motion.

Next, your veterinarian will perform a lameness exam, watching the horse in motion on a straight line and circle. They may perform a flexion test to simulate stress on the joint. [14]

Once your vet is confident that the lameness is associated with the fetlock, a combination of diagnostics may be necessary to determine the type of injury present. Radiographs of the joint assess changes to the bones, such as fractures or osteoarthritis. Ultrasound of the soft tissue structures around the joint identify injuries to the tendons, ligaments, and joint capsule.

If fetlock injury is apparent, but neither x-rays nor ultrasound reveals any diagnosis, your veterinarian may refer the horse for additional imaging such as CT or MRI.

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Anatomy of the Fetlock Joint

The fetlock in horses is known as the metacarpophalangeal joint. It lies at the distal (far) end of the third metacarpal bone (cannon bone) and the proximal (close) end of the first phalanx (long pastern).

The fetlock also contains the two proximal sesamoid bones, which are small bones that lie at the rear of the fetlock joint. [4]

The hind fetlock joint is classified as a hinge joint because its motion is restricted to forwards and backwards.

The fetlock is surrounded by a joint capsule that contains synovial fluid. Synovial fluid lubricates the joint and provides nourishment to the articular cartilage. [4]

Image from Denoix, J.M. Essentials in Clinical Anatomy of the Equine Locomotor System.

1- third metacarpal bone (cannon bone); 11 – proximal phalanx [27]

Soft Tissue Structures

There are several soft tissue structures associated