Progress on a Diagnostic Test for DSLD/ESPA

Scientists at the University of Georgia's College of Veterinary Medicine are studying a new diagnostic test that will detect a common disease of the musculoskeletal system of the horse before he exhibits lameness or other performance problems. The test will detect excess accumulation of proteoglycans--molecules that help organize connective tissue so that it is elastic, yet strong--and thus catch equine systemic proteoglycan accumulation (ESPA) before it debilitates the horse.

The test involves microscopic examination of a thin sliver of tissue, about the size of a human fingernail, from the nuchal ligament (at the back of neck).

 

A: Photomicrograph of normal nuchal ligament shows uniformly stained (pink) connective tissue. The small blue dots are nuclei of fibroblasts, the main cells of connective tissue. B: Photomicrograph of nuchal ligament from a horse affected with ESPA. Small pools of light blue staining indicate excess proteoglycans (marked with arrow).

IMAGES COURTESY BMC PAPER AND DR. JAROSLAVA HALPER

The condition ESPA is more commonly known as degenerative suspensory ligament desmitis (DSLD), but researchers renamed it in light of this study because they found the condition in tissues other than the suspensory ligament of the leg.

Jaroslava Halper, MD, PhD, lead author on the paper, says, "Researchers originally identified and determined that the disorder affected only the suspensory ligament because the number one clinical sign for this disorder is lameness." In some severe cases, horses might even have hyperextended fetlocks.

However, Halper said that in additional to lameness, "Several breeders brought to my attention that many of their affected horses also developed so-called fallen crests on the back of their necks." Halper began to wonder if ligaments in the neck were somehow affected by the disease.

David Burrell, a horse owner in Collins, Ga., and a great supporter of Halper's research, alerted Halper to unusual cases of ESPA on different horse farms several years ago. Quite a few of his ESPA-affected horses had died quite suddenly from aortic ruptures. That prompted Halper to examine the aortas and coronary arteries of ESPA-affected horses.

In the study published in the April 12 issue of BMC Veterinary Research, Halper and her colleagues examined tissues and organs from 28 horses (22 Peruvian Paso horses, one Arabian, one Hanovarian, one Appaloosa, and one Quarter Horse) that had the disorder, at least 16 of which had known family histories of DSLD, and they sampled from a control group of eight horses that did not have the disorder. When viewed under a microscope, tissues from various ligaments in affected horses' bodies as well as vessels and organs with significant amounts of connective tissue showed an abnormal accumulation of proteoglycans.

Once the diagnostic test is developed further, it is Harper's hope that horse owners will be able to minimize the occurrence of the disease through selective breeding.

To read more about the original study, see www.TheHorse.com/ViewArticle.aspx?ID=7219.


 

About the Author

Rachael C. Turner

Rachael Turner is the former Photo and Newsletter Editor for The Horse. She is an avid event rider. Rachael's main focus is dressage and on training young horses with the proper foundation for success. She is also a member of the United States Dressage Federation and the United States Equestrian Federation. Her website is avonleaequestrian.com.

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