The vet’s aims are to eliminate any predisposing causes such as poor foot balance or inappropriate shoes, to reduce inflammation by the use of cold therapy, laser treatment or therapeutic ultrasound and to encourage good quality repair of the damaged fibers.
Small lesions at the top of the suspensory ligament often resolve with around three months’ box rest, combined with a controlled exercise program. Scanning can be used to monitor healing. Larger injuries in the body or branch may need surgery to remove any blood clots. Prolonged rest combined with an ascending exercise program is an essential part of any treatment regime.
The prognosis depends on many factors including:
- the site of the injury
- the severity of the injury
- the duration of the injury
- the future athletic expectations for the horse
Most horses are able to return to some level of work, but there is also a big chance of reoccurring injury.
With appropriate early treatment most horses with a sprain around the origin of the ligament make a complete recovery; however, the chance of repeat damage to injuries on the body of the ligament is quite high if the horse returns to its former workload. The prognosis for branch injuries is between the other two.
Some factors may predispose the suspensory ligament injury in horses or injury’s recurrence:
- conformation can play a role. A horse with a crooked lower limb will overload one side of the fetlock and predispose it to a branch injury
- poor foot balance is commonly seen in horses that injure the origin of the ligament. If the shoes are too short and offer little support to the back of the heel region, this can cause an overload of the ligament
- fast work: there is also no doubt that suspensory ligament injuries are an occupational hazard for some horses, particularly those which jump at speed
- a previous suspensory injury also places a horse at increased risk of repeat injury since, particularly with body and branch injuries, the repair tissue is never as strong as before
Suspensory Ligament Injury in Horses (and The Treatment) General description
Ligaments attach bones to each other and act as supports. The suspensory ligament in the horse is a strong, broad, fibrous anatomical structure that attaches to the back of the cannon bone just below the knee — the origin of the ligament.
About two-thirds of the way down the cannon bone, the ligament divides into two branches which attach to the inside and outside sesamoid bones, on the back of the fetlock.
In the upper third of the cannon region, the suspensory ligament lies between the large “heads” of the splint bones. This means it is impossible to feel the ligament, or apply pressure directly to it, so the diagnosis of damage is difficult.
Horse suspensory ligament injuries and their signs
A sprain of the horse suspensory ligament (suspensory desmitis) is usually restricted to one of three areas:
- injury to the upper third of the ligament (called high, or proximal, suspensory desmitis) is common in horses in all disciplines
- injury to the middle third, or body, of the ligament, is easiest to diagnose, but least frequent. National Hunt racehorses and point-to-pointers are most likely to suffer this injury
- damage to the inside or outside a branch of the suspensory ligament is also common, particularly in horses that jump
A suspensory ligament injury in horses causes heat, swelling, and pain
When the middle third, or body, of the suspensory ligament, is sprained the signs are easy to detect as there is often obvious swelling. It usually occurs on both the inside and outside of the leg, contrasting with swelling associated with a tendon strain, which happens to the back of the leg.
Heat is easily felt. The horse will also resent palpation of the injured part of the ligament, the edges of which may be rounded and poorly defined. The ligament may feel softer than normal.
There is usually some lameness, the degree of which often reflects the severity of the injury. However, the lack of lameness does not mean there is no significant injury. With a severe injury, the whole area may be swollen so it can be difficult to assess which part of the ligament is primarily involved.
Cold therapy and bandaging will usually reduce the swelling, making a definitive diagnosis easier. Alternatively, a vet can determine which part is involved and assess the extent of the damage using an ultrasound scanner.
An injury to the inside or outside a branch of the ligament will cause swelling on one side of the fetlock. Do not confuse this with swelling due to direct trauma, such as getting cast.
Lameness associated with a branch injury can be mild to moderate but may improve within days. Again, scanning will confirm the extent and severity of the injury and determine whether there is concurrent damage to either the sesamoid bone or the splint bone on the same side. X-rays may also be needed.
Damage at the top of the suspensory ligament invariably causes lameness — varying from mild to severe — which, if the horse rests, can improve rapidly. The lameness tends to be worst when the horse moves in circles with the affected limb on the outside. Slight localized heat may appear when the lameness is acute, while in subtle cases thermography can detect this. The vein which runs down the inside of the cannon region may be enlarged.
