Description

The sesamoid bones in the legs of the horse act as "pulleys" for the suspensory ligament that helps move the leg as it passes over the back of the fetlock joint. The pulley action is similar to that of the navicular bone in the horse's foot.

Sesmoiditis describes the condition that exists when the sesamoid bones at the back of the fetlock joint become inflamed and are unable to work properly. Sesamoiditis is most common in athletic horses that place extreme stress on the sesamoid bones during high-speed exercise and jumping.

Overweight horses and horses with long pasterns and low heels also seem to be more prone to development of sesamoiditis. In some cases horses may inherit the tendency fo sesmoiditis and a genetic component to the condition may exist.

Symptoms

• Lameness
• Sensitivity to pressure on sesamoid bones
• Warmth felt at fetlock joint
• Swelling or thickening around fetlock joint

Causes

The cause of sesamoiditis is stress to the sesamoid bones during high-speed exercise, possibly coupled with a faulty blood supply to the bone. Faulty blood flow is aggravated by concussive jolts, and, combined with the stress on ligament attachments, results in inflammation, pain, and demineralization of the bone.

Prevention

Preventing sesamoiditis in athletic horses is difficult, but efforts can be made to limit exercise on hard surfaces and to act promptly when bruising of the sesamoid bones or strain on the sesamoid ligaments is suspected. Weight management of horses is also important, since overweight horses appear to be more prone to the condition.

Treatment

Treatment of sesamoiditis begins with a definitive diagnosis made by taking X-rays of the fetlock joint and sesamoid bones. If sesamoiditis is diagnosed based on the X-rays, using ultrasound to assess any damage to the suspensory ligament and distal sesamoidian ligaments will be the next step.

Reducing inflammation by alternating hot and cold therapies and poultices on the fetlock are effective treatments. The horse must be rested and confined. Depending on the degree of injury, a Paten shoe may help by lifting the heels, and a strong elastic bandage will provide support for the joint.

Some veterinarians also recommend egg bar shoes with squared toes and a wide roll or bevel to ease breakover and reduce stress on the suspensory apparatus.

Non-steroidal anti-inflammatory drugs will help reduce inflammation and a veterinarian may suggest intra-articular treatment of the fetlock joint with hyaluronic acid to reduce inflammation in the joint.

Shock wave therapy has been used with varying degrees of success in the treatment of sesamoiditis. Your veterinarian is the best source of information as to what will work best for your horse.