Injuries to the suspensory ligament are a common problem in horses.

They affect all breeds and ages but are particularly a problem in competition horses, where inflammation of the suspensory ligament (desmitis) can occur in the fore or hindlimbs and has several presentations.

The suspensory ligament is the most important structure that supports the fetlock joint (probably why it’s called the suspensory ligament).

This article aims to give some background information about the anatomy, areas of damage and how desmitis can be diagnosed and treated.


The suspensory ligaments originate at the top of the back of the cannon bone, just under the knee and the hock. They travel downwards between the splint bones and then divides into two branches to attach onto the two sesamoid bones at the back of the fetlock joint.

The upper third (origin) of the suspensory ligament is also known as the proximal suspensory ligament. The middle part (the body) is predominantly between the two splint bones (Fig 1) and just like the proximal area contains some muscle tissue which can become stronger with training.

The two branches are found in the lower third of the cannon area. Several short ligaments run from the base of the sesamoid bones down the back of the pastern and are called the distal sesamoidean ligament (injuries to these structures are much less common and are not to be discussed in this article).

Like all ligaments and tendons, the suspensory ligament is subject to overload. It acts as a sling for the fetlock in the fore and hind limbs and is more likely to be injured in older horses and in those with a straight hind limb conformation (Fig 2). Often both limbs are affected.

Proximal suspensory desmitis (PSD)

The origin of the suspensory ligament is put under stain, particularly in sports horses which are required to ‘engage the hindquarters’.

These injuries appear to be more common on horses trained on soft surfaces. Microscopic damage to the collagen fibrils builds up over time and causes long term changes in the ligament.

Lameness often gradually develops and owners often initially only notice a reduction in performance, rather than lameness. There is usually no heat or swelling associated with this problem.

Sometimes a small piece of bone can also be pulled (avulsed) off the back of the cannon bone concurrently with PSD.

The prognosis for a horse to return to full soundness is better in the forelimb than the hindlimb, with many of the latter permanently lame.


body desmitis

The central part of the suspensory ligament is most commonly injured in Thoroughbred and Standard-bred racehorses, but pleasure and sports horses can also be affected.

It is important to be vigilant when checking the horse's limbs after exercise as often any lameness may seem to be mild or absent in these cases. Heat and swelling can be felt mid-cannon region in front of the flexor tendons (Fig 1).

Sometimes the splint bones can be damaged by the swollen ligament so x-rays are often taken when this condition is diagnosed.

Usually the ligament will heal reasonably well, but re-injury is not uncommon.

Desmitis of the branches of the ligament

In most horses it is usually only one of the two branches that are injured. However, in old horses, it is more common in both.

The injured area is usually warm and swollen when damaged. Lameness is not always present so it is worth investigating any swellings around the back of the lower cannon/ upper fetlock region.

Horses are more likely to strain the branches if the foot is not correctly balanced or the horse has excessively bent limbs. All types of horses can be affected and, unfortunately, re-injury is also common. In the past many horses with desmitis of the branch/branches where stated to have sesamoiditis.

Breakdown of

the ligament in older horses

The collagen in ligaments and tendons becomes weaker with age, therefore, in geriatric horses, the suspensory ligament gradually stretches and becomes less elastic, especially in the hind limbs.

The fetlock has less support so moves lower towards the ground. A straight hock and stifle conformation has also been associated with weakened suspensory ligaments in an older horses (Fig 2).

This condition can be painful and the horse may shift weight from limb to limb more often than is normal.

Unfortunately, the suspensory ligament can break down completely in very severe cases and euthanasia may have to be undertaken


Usually, a combination of a good veterinary clinical examination and imaging tests will be needed to make an accurate diagnosis.

A flexion test will often worsen the lameness if desmitis is present in any part of the ligament. Nerve blocks, using local anaesthetic to desensitise the nerve serving the suspensory ligament, can be instrumental in helping to in localise the source of the lameness.

Ultrasound scans can show a variety of changes to any part of the suspensory ligament. Changes found in scan include enlargement, focal damage or widespread degeneration.

X-rays can be used to check for damage to the adjacent cannon, splint or sesamoid bones. Occasionally, a bone scan (nuclear scintigraphy) is required to locate the problem. MRI can also be of use in less obvious cases.


Where an acute injury is present, anti-inflammatory therapy is useful to reduce ongoing damage.

This can include bandaging, cold hosing, ice packs and in-feed anti-inflammatories such as Danilon. Box rest is essential at this stage.

With chronic injury, treatment is usually based around rest and controlled exercise. Free exercise is usually not permitted initially in order to give the ligament a chance to heal without being re-strained.

Controlled exercise, however, often helps as it encourages the laydown of new collagen fibers which can align themselves in an ordered formation. The repaired ligament will not be as strong as the original ligament, and may never look normal on ultrasound scan.

Injured suspensory ligaments usually to take several months to heal, perhaps up to one year or even longer in rare cases – and PSD can be particularly difficult to treat, especially in the hind limbs.

The use of extracorporeal shock wave therapy can help to reduce local inflammation and improve the long-term prognosis. However, as many cases may require surgical treatment in the form of neurectomy/fasciotomy to regain soundness.

This surgery has a reasonably good prognosis in the short term (one-two years). Even if a horse does not recover well enough to return to its original use, it may manage to work at a lower performance level.

Anti-inflammatory therapy can be used long term in some cases. Good farriery will help to maintain correct foot balance and appropriate shoeing will provide some support to the function of the suspensory ligament.

If you suspect your horse is suffering from such an injury, contact your local vet.