Degenerative Suspensory Ligament Desmitis in Horses: DSLD Signs and Progression

Degenerative Suspensory Ligament Desmitis, usually called DSLD, is a chronic, progressive disease that affects the suspensory ligaments and other connective tissues in horses. Unlike a simple athletic strain, DSLD is not caused by one bad step or one hard workout. Instead, the ligament tissue gradually loses normal structure and support, which can lead to pain, instability, and a lower or "dropped" appearance of the fetlocks over time.

DSLD was first recognized often in Paso breeds, but it has been reported in many other horses as well. Current veterinary sources describe it as a degenerative condition rather than a routine overuse injury. That matters because some horses show changes in more than one limb, and the disease can continue to progress even when work is reduced.

For pet parents, the hardest part is that DSLD can start subtly. A horse may look mildly off, feel stiff, or seem less willing to collect, turn, or work on certain footing. Later, the signs become easier to see. The fetlocks may sink lower, the gait may shorten, and comfort can decline.

Because DSLD is progressive and irreversible, the goal is not to "fix" the ligament. The goal is to work with your vet to confirm what is happening, reduce pain, support the limbs, and choose a care plan that matches your horse's comfort, use, and long-term quality of life.

The exact cause of DSLD is still not fully settled, but current veterinary sources support that it is not the same thing as a routine suspensory strain from exercise. Research and clinical experience suggest a heritable or genetic component in at least some horses and bloodlines. That helps explain why the disease has been recognized more often in certain breeds and families.

DSLD is considered a degenerative connective tissue disorder. In practical terms, that means the ligament tissue changes over time and becomes less able to support the fetlock normally. Some articles and researchers also use the term equine systemic proteoglycan accumulation for related disease concepts, although the exact pathology and naming remain an area of ongoing study.

Importantly, normal work alone does not appear to be the root cause. Exercise, hoof imbalance, body condition, and footing may worsen discomfort or make signs more obvious, but they do not fully explain why affected horses develop the disease. Many pet parents feel guilty when a horse is diagnosed. In most cases, this is not something you caused.

Because there appears to be a breed and family pattern, breeding decisions matter. If a horse has confirmed or strongly suspected DSLD, your vet may advise against breeding that horse and may recommend discussing related horses with breeders or breed organizations.

Diagnosis starts with a full history and lameness exam. Your vet will look at how your horse stands, walks, and turns, and may palpate the suspensory branches for pain or thickening. Because DSLD can affect more than one limb, the gait changes are sometimes less dramatic than with a single acute injury.

Many horses need diagnostic analgesia, often called nerve blocks, to help localize where the pain is coming from. Imaging is then used to look for structural changes. Ultrasound is especially helpful because it can show disruption of the normal fiber pattern in the suspensory ligament, sometimes even before the fetlocks look severely dropped. Radiographs may also be used to rule out other causes of lameness or to assess related changes around the fetlock and sesamoid region.

Diagnosis is usually based on the combination of clinical signs, imaging findings, and progression over time. In some cases, your vet may also discuss advanced imaging or biopsy, but these are not needed for every horse. The main challenge is distinguishing DSLD from other suspensory injuries, arthritis, neurologic disease, or hoof pain.

In the US, a basic equine lameness exam often runs about $250-$500, with limb ultrasound commonly adding about $150-$300 per region and radiographs often adding $40-$75 per view. Therapeutic planning after diagnosis can increase the total, especially if medications, repeat imaging, or specialty farrier work are needed.

There is no proven way to fully prevent DSLD in a horse that is genetically predisposed. Because the disease appears to have a heritable component, the most meaningful prevention step is often breeding selection. Horses with confirmed DSLD, or those from strongly affected family lines, should be discussed carefully with your vet before being used for breeding.

While you may not be able to prevent the disease itself, you can often reduce strain on affected tissues and catch problems earlier. Keep your horse on a regular farrier schedule, pay close attention to hoof balance, maintain an appropriate body condition, and avoid asking a sore or unstable horse to continue demanding work. Good footing and sensible conditioning also help reduce added stress on already vulnerable limbs.

Early recognition matters. If your horse develops repeated suspensory soreness, unexplained bilateral lameness, or a gradually lower fetlock angle, do not assume it is normal aging or a minor strain. Prompt evaluation gives your vet a better chance to build a comfort plan before the disease becomes advanced.

For horses already diagnosed with DSLD, prevention shifts to preventing secondary problems. That may include reducing flare-ups, limiting overwork, supporting the feet, and watching for complications such as osteoarthritis, laminitis risk from reduced mobility, or worsening pain that affects daily comfort.