Degenerative Suspensory Ligament Desmitis (DSLD)
Degenerative Suspensory Ligament Desmitis (DSLD) is a progressive disease of connective tissue and a common cause of horse tendon injuries, specifically affecting the suspensory ligament in horses. Once believed to be a condition associated with old age or overuse, DSLD is now understood as a systemic disorder meaning it impacts more than just the suspensory ligament in horses’ legs with a likely genetic basis. Also referred to as Equine Systemic Proteoglycan Accumulation (ESPA), it is a chronic and progressive disorder that affects the connective tissues of horses. The condition was first observed in Peruvian Paso horses, however, it is not limited to this breed—it has also been identified in Arabians, Quarter Horses, Warmbloods, Paso Finos, Saddlebreds, and others.
The biochemical pathway of DSLD is caused by an abnormal accumulation of proteoglycans in the extracellular matrix of connective tissue. Proteoglycans are glycosylated proteins that normally provide structure and elasticity to connective tissue. In DSLD, however, these molecules are found in excessive amounts and with altered composition, weakening the ligaments and tendons rather than supporting them.
Underlying biochemical factors in combination with biomechanical challenges lead to hyperextension of joints, particularly in the fetlocks, hocks and stifles. Affected horses may present with signs of lameness, enlarged suspensory ligaments, “dropped” fetlocks, heat and swelling in the joints, stumbling, and possible behavioural changes due to pain.
Diagnosis
Diagnosis can be difficult in the early stages, as symptoms can mimic other conditions of the distal limb. In more advanced cases, diagnosis is made through physical palpation, flexion tests, and ultrasound of the suspensory ligament. The use of UTC (Ultrasound Tissue Characterisation) is particularly useful as this technology can reveal abnormalities in ligament structure, degree of degenerative fibre patterns, and the response of the ligament to exercise.
How to Care for Horses with DSLD?
DSLD is, per definition, a degenerative condition and in that way is often seen as a “one way street”, and nothing can be done. Although this is largely true for the biomechanical aspect of the condition, this is not the case with regards to the biomechanical influence on the progress of the condition.
Despite ongoing research, there is currently no cure or established method to slow the progression of DSLD, however, early intervention will alter the speed and severity of negative changes.
Horses with DSLD can degenerate over time as a result of biochemical processes within the ligaments themselves, in combination with the biomechanical challenges associated with use of the limb. Age is an additional factor, and eventually the horse reached a “tipping point”, after which, weakened ligaments and relative overloading leads to a collapse of the supportive suspensory apparatus.
Use of the TendonPro Dynamic Support System will remove the biomechanical challenges to a large extent, supporting the MCP joint and maintaining better joint angles in the distal limb whilst in use.
Considerate and timely use helps the body to resist the biomechanical challenge and this can mean the horses body is in a better position to slow down, or even reverse the biochemical changes.
Current supportive care is limited, but includes therapeutic shoeing to help stabilize the fetlocks, balanced fitness and training protocols, and, in inflammatory stages, the use of nonsteroidal anti-inflammatory drugs. Diets should be low in sugar and starch, as these can increase inflammation, and should include fibre-based feeds. Omega-3 fatty acids have shown promise in supporting joint health and reducing inflammation as well. Supplements like MSM may also improve connective tissue resilience and reduce pain.
Early data from protocols using a dynamic fetlock supporting device (TendonPro DSS) suggest that dynamic support leads to breaking the above mentioned negative spiral, and leads to stabilization of active inflammatory stages of the condition, slows down the degenerative cycle and improves fibre alignment in the suspensory ligaments. This data also shows that temporal use of the device at the time when first (minimal) symptoms are showing can avoid escalation and speed of degeneration of the ligament.
The TendonPro DSS mechanically supports the MCP joint, and so positions the distal limb with enhanced fetlock and pastern angles. The horse can wear the device for long periods and can exercise in them at all gaits. User protocols ranging from long-term use to temporary application (e.g. late-term mares, stallions during semen collection, painful episodes, or anticipated high loading before competition) have been shown to improve fetlock angles, either permanently or semi-permanently.
Call to Action
At Equine Tendon, we’ve seen encouraging results using the TendonPro DSS in managing DSLD cases — including many initially considered hopeless. Our experience suggests that, with consistent care and targeted support, it’s possible to significantly improve both comfort and mobility for affected horses.
At Equine Tendon, we are currently compiling real-world case studies to highlight the potential for improved quality of life in horses diagnosed with DSLD. If you are currently managing this condition in any of your patients, or clients horses — or if you have a case that has shown measurable improvement while using the TendonPro DSS Boot — we would love to hear your story. Your experience may contribute to a broader understanding of effective management strategies and offer valuable insight for others facing similar challenges.
Please fill out the form below if you would like to be apart of the case study.