Peruvian Paso, Arabian, American Saddlebred, and American Quarter Horse owners have been patiently waiting for an update on the diagnosis and treatment of equine systemic proteoglycan accumulation (ESPA). While no new data has been published recently, researchers have been working diligently to make progress in this field.

ESPA is a "new" name for an old disease: degenerative suspensory ligament desmitis (DSLD), a heritable, debilitating syndrome characterized by "an insidious onset of either bilateral or quadrilateral lameness with no history of trauma or injury," according to P.O. Eric Mueller, DVM, PhD, Dipl. ACVS, professor of surgery and Director of Equine Programs at the University of Georgia Large Animal Veterinary Teaching Hospital.

The condition was (and often continues to be) referred to as DSLD because it was widely thought to affect only the suspensory ligament. Either way, the condition is often progressive, leading to recurrent, incurable lameness and, oftentimes, euthanasia. The underlying cause is an overabundance of molecules called proteoglycans (part protein, part carbohydrate) in the suspensory ligament.

In 2006, researchers found that the excessive accumulation of proteoglycans occurred in a variety of anatomic structures with high amounts of connective tissues