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Ligament Injuries - how to diagnose and treat them

By James Tate BVMS MRCVS
First Published: 08 April 2009 - Issue Number: 12

Ligament injuries have led to the retirement of many of horseracing’s great heroes. The list of equine superstars who were forced into quitting the track include Champion two-year-old male of 2002, Vindication; the ever-popular grey Evening Attire; Champion older female of 2006 Fleet Indian; as well as Grade One winners Heatseeker, Zaftig (below) and Dance Smartly. Ligament injuries do not always lead to retirement but they are serious and must always be treated with extreme caution.

A ligament is a tough band of fibrous tissue that connects bones or cartilages. There are approximately one hundred different types of ligament in the horse but a select few cause equine veterinarians problems time and time again.  These ligaments are anatomically designed to be tough and relatively inelastic; however, the side-effect of this is that they do not heal well from injury and as a result have disappointing recovery rates. If the horse is fortunate, the injury may become apparent at a relatively early stage when it is no more than a simple inflammation or ‘desmitis.’ However, if the horse is not so fortunate, it may suffer from a ligament tear, which is a very serious injury.
Given the large variety of ligaments in the horse it is difficult to group them together, but ligament injuries do tend to behave in similar ways. Diagnosis is usually straightforward, as an affected ligament is hot, swollen and painful and the difference in diagnosis only comes from the position of the ligament. For example, a suspensory ligament injury is usually obvious for all to see as its position makes it easy to feel and an ultrasound scan is only required to establish the severity of the injury and to monitor healing. However, diagnosis of a joint ligament injury is more challenging and relies either on an assumption or a good ultrasonographer to pinpoint the affected area.

Suspensory Ligament Injuries
The suspensory ligament is perhaps the best-known ligament of the horse. Strictly speaking, this ligament is the equivalent of an interosseus muscle found in other animals, however, in the horse it is composed of tough fibers and there is only a small amount of muscle tissue present. It originates from the back of the knee (or hock in the hind leg) and runs down the back of the cannon bone until splitting into two suspensory branches in the lower third of the cannon. Each branch then has a portion that attaches to a sesamoid bone with the remaining ligament traveling round to the front of the pastern. This complex anatomy creates two common different injuries – upper suspensory body injuries and suspensory branch injuries. Injuries at both sites can be mild or severe although generally the younger the horse, the better its chance of recovery.
Injury to the upper body of the suspensory ligament is a common event in the Thoroughbred as it is caused by stress, which the limbs of the racehorse receive in abundance. Affected horses are often lame with an enlarged, hot, painful upper suspensory ligament. The lameness improves quickly with rest and regional nerve blocks confirm that this is the area of pain. Ultrasound...

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