Desmitis of the Suspensory Ligaments of the Leg in Horses

The suspensory ligaments are the ligaments that support a body part. The long suspensory ligaments that are located in the lower legs can become inflamed and swollen. This swelling of the ligaments is referred to medically as desmitis and can cause varying degrees of lameness in the affected horse. Desmitis, and the underlying damage to the ligament, often take several weeks or even months of restricted exercise to heal, even after more advanced treatments.

Desmitis is the medical term for when the ligaments become inflamed and swollen. For equines, this tends to occur most often in the joints of the legs.

The symptoms of desmitis inducing ligament damage in the leg are primarily the same symptoms and signs you would see with any horse suffering from lameness. 

• Behavior changes
• Generalized limping
• Inability to put weight on the limb
• Heat at site of damage or swelling
• Poor performance
• Reluctance to stand 
• Swelling

When the injured ligament is affecting the front legs, the horse will often lift its head higher when stepping on the distressed limb, and drop it when putting the weight on the sound limb. When a hind leg or foot is involved the disorder will be most apparent when viewing the horse from behind. When the horse walks, it will lift its hip on the lame side to avoid putting as much weight on it and will allow the other side to dip a little bit to compensate. 

Types 

Injury to the ligament often causes desmitis, and can usually be classified by where the damage and swelling are occurring. 

• Swelling high on the suspensory ligament, also known as proximal desmitis may not show any external signs of swelling beyond lameness as it is somewhat hidden behind other structures in the leg. 
• Desmitis that occurs in the middle portion of the ligament his is the least common type of damage and swelling, but it tends to be easier to diagnose damage in this than in the other sections.
• About two-thirds of the way down, the ligament splits into two branches; when swelling and damage occur in either one or both of these branches, it can sometimes cause a bit of the sesamoid bone to break off

Several factors can cause a specific horse to be more likely to develop desmitis of the suspensory ligament. These can include:

• Jumping and racing athletes - Horses who spend a great deal of jumping or running put additional strain on the ligaments of the leg, and as a result, are more prone to damage of the suspensory ligament
• Poor conformation - Horses with crooked limbs may overload one branch of the ligament after the split
• Shoeing problems - Shoes that do not offer enough support for the back of the heel can cause the suspensory ligament to be overburdened

When dealing with lameness or pain in the limbs of a horse, the diagnosis has two primary goals. The first goal is to determine from which part of the leg the pain or weakness is originating. The second goal is to identify what the underlying cause is so that an appropriate treatment plan can be selected. Diagnosis will usually start with a complete physical, with particular attention being paid to the legs and feet. A full history of the animal, including its activity levels, diet, and living conditions, may help determine the cause of the injury or weakness as well. A flexion test and lameness exam will generally be conducted by the examining veterinarian as well, to evaluate the animal moving at different gaits.

Local nerve blocks are also quite helpful in diagnosing where the pain is located on the suspensory ligament. A complete blood count and biochemical profile will help establish if any infections are present, and a lactic acid test may either confirm or rule out laminitis, a disorder that can have severe consequences if untreated. Tendons and ligaments do not show up on x-rays, but the swelling and any underlying injuries are often found using alternative imaging techniques, such as ultrasound, MRI, and scintigraphy.

The first step in treating desmitis of the suspensory ligament is to reduce the swelling and the heat. NSAID pain management medication is frequently employed to reduce the inflammation and swelling both of the ligament and of the tissues surrounding it, and cold hosing or icing will help lessen the heat of the affected leg. It is essential only to use NSAID drugs as directed as they can become toxic at higher doses. Rest and hand walking are standard recommendations for lame horses, regardless of the underlying cause, and are used to reduce the load on the leg that is affected so that healing can take place. Lameness can often be helped by proper shoeing.

With suspensory ligament damage, this can mean choosing a shoe with additional heel support, providing the horse with specialized hospital shoes that cover the bottom of the foot and are designed to quickly open to give ready access to caregivers, or even creating shoes specifically for that horse, used most often for horses with limb deformities or abnormalities. Advanced therapies such as shockwave therapy, platelet-rich plasma, and stem cell therapy have been found to be quite useful in healing damage to ligaments.

If your horse needs equine surgery, you will be given specific instructions from your veterinarian regarding post surgery care for your horse.  In most cases, stall confinement will be necessary for a short time to facilitate healing and regrowth. This can be a difficult transition for many animals, and depending on the temperament of the horse, sedation may be needed to keep the animal tranquil during this healing period. Restricted exercise will be required after your horse is released from stall rest for full healing of the ligaments in the leg. Once they are steady enough to be out of their stall for exercise, they may require close supervision or hand-walking until they are suitably restored.