What is the best way to support a horse affected by a ligament injury? Unfortunately, due to the nature of many equine disciplines, a horse’s ligaments are prone to injury.

In fact, ligament sprains (along with tendon injuries) are the most frequent cause of early retirement for Thoroughbred racehorses. [1]

Ligaments are a type of connective tissue made of strong, fibrous material that group together in bundles to form long cords. Ligaments connect adjacent bones in the horse’s body and have two main functions: keeping bones aligned and providing support for joints.

Eventing, racing, and other forms of competition all put significant strain on a horse’s tendons and ligaments, increasing the risk of injury. Degenerative changes that occur with ageing can also predispose a horse to a ligament injury. [2]

While some horses do make a full recovery and return to work, healing ligaments is more difficult than healing other tissues. The horse’s body can produce new connective tissue to repair ligaments, but rarely will they match the ligament’s original strength and function.

However, with some of the newer veterinary therapies available, horses may have a more hopeful prognosis. This article will review types of ligament injuries in horses and how to support recovery.

Ligaments of the Horse’s Legs

Horses have a number of different ligaments throughout their body, but the most commonly injured ligaments are located in the legs.

The following ligaments are most commonly affected by injury in sport horses:

Collateral ligaments stabilize a joint as it flexes and extends through its range of motion. The most commonly injured collateral ligaments in horses are located in the coffin, fetlock, and hock joints.

Palmar annular ligament of the fetlock, which starts from the sesamoid bones and stabilizes the flexor tendons, especially the superficial flexor tendon

Accessory (check) ligament of the deep flexor tendon, which runs from the carpus (knee) on the back of the leg and attaches to the deep digital flexor tendon about one-third of the way down on the cannon bone. This ligament helps with shock absorption and prevents excessive lengthening of the deep digital flexor tendon

Meniscal and cruciate ligaments on the upper hind legs. Both of these ligaments help to stabilize the horse’s largest joint: the stifle joint.

Suspensory ligament which supports the fetlock and protects it from hyperextension. This ligament is attached to the upper cannon bone in both the front and hind legs. It runs downward near the back of the cannon bone before dividing into two branches which attach to one of the sesamoid bones at the back of the fetlock.

Types of Ligament Injuries

Most ligament injuries occur in the horse’s forelegs since they bear 60% of the horse’s overall weight and are more likely to endure concussion.

The severity of a ligament injury can vary from a mild sprain to something more serious such as a tear or even a rupture. Depending on the type and severity of the injury, the treatment plan will vary as well.

The following are the classifications of ligament injuries:

Type I Lesions

Strains typically cause ligaments to stretch, resulting in swelling. The affected area usually becomes slightly enlarged, warm to the touch, and painful. Lameness may or may not be present.

Type II Lesions

Mild ligament tears are more serious than strains and usually result in increased swelling, heat, and often (but not always) lameness.

Type III and IV Lesions

Severe ligament tears are classified as Type III lesions while massive tearing is classified as a Type IV lesion. Type IV lesions result in severe lameness, obvious heat, pain, and swelling.

Injury Severity and Location

The more severe the ligament injury, the more lameness the horse will experience.

Of all the ligament injuries that can occur in a horse, inferior check ligament injuries are the least severe. Suspensory ligament injuries are the most common and also the most serious, as well as the most difficult to treat.

Suspensory ligament injuries may occur from a single traumatic event or they may be associated with chronic degeneration over time.

Because the suspensory ligament is so often affected in sport horses, injuries to this ligament are subdivided into three main categories depending on the location in which they occur:

  • Suspensory injuries affecting the upper third, typically called proximal suspensory desmitis
  • Injuries affecting the body of the suspensory ligament
  • Injuries affecting the branches of the suspensory ligament

The suspensory ligament is also affected by the genetically inherited condition Degenerative Suspensory Ligament Desmitis (DSLD) which results in progressively worsening pain and lameness.

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