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| Return to Home Page Diagnosis CERTAINLY, ONE SHOULD NEVER RUSH TO A DIAGNOSIS OF DSLD, but to rule it out too soon leads to prolonged suffering. Horses have gone misdiagnosed (and mistreated) for years, only to be confirmed with DSLD post mortem. On the other hand, there have been horses that were diagnosed early on, but when the disease didn't progress as expected, owners understandably were relieved, doubted what later proved to be valid diagnoses and abandon prescribed treatment - much to the horse's detriment. Early diagnosis is key to successful management of DSLD. But initial signs, such as discreet gait or stance changes, can be easy to miss. Breeders point out that the natural stoicism and heart of some horses make them especially difficult to diagnose early, as what is happening on the inside is not always reflected on the outside. At the other extreme, the symptoms of a chronic case recently seen by one veteran practitioner were "so obvious, you could have diagnosed it through the windshield". Those most familiar with DSLD emphasize that physical and ultrasonic examination by a qualified veterinarian, familiar with the syndrome, is the method of choice for diagnosis. Newer diagnostic tools, such as nuclear scintigraphy and thermography can catch changes even before ultrasound. Unfortunately, relatively few are competent to accurately diagnose DSLD. Vet schools see cases in their equine clinics, yet admit they include little formal education on it in their curriculums. A leader in the field comments, "Sonogram changes on ultrasound start early on ? I do not look for tears, per se ? that is not what we see, usually. The first signs on ultrasound are a thickening of the ligaments (in the branches first) showing up as an increase in the white color of the ligaments on the screen. And usually an increase in the size of the ligaments, even if subtle. Again these are reasons why this is missed - most vets are looking for obvious tears. As time goes on the branches continue to thicken, enlarge and eventually holes or defects can sometimes be noted, but not always." Ultrasound often reveals a random fiber pattern that does not line up with the "grain" of the original collagen fibers. Radiographs, or X?rays, can confirm the lowering of the sesamoid bones, mineralization in the suspensory branches, changes in the pasterns as the horse becomes coon? footed, and secondary arthritic changes. Infrared thermography, which measures heat patterns, shows excess heat in the suspensory ligament and its branches early on. Nuclear scintigraphy, in which the horse is injected with a radiographic substance then scanned with a gamma camera, zeroes in on "hot spots" that literally "light up" on the screen. The Genetic Connection PERUVIAN HORSES have been singled out as "known" for DSLD. Recently, the Peruvian Paso Horse Registry of North America (PPHRNA) approved a clinical study to either rule out, or substantiate any genetic link. Several diagnosed horses have been full or half sisters or brothers. But saying "it's genetic" won't solve anything unless a method of transmission is proven. If it is inherited, it may be no simple dominant or recessive trait. There could be genetic variables such as modifiers, linked genes and incomplete penetrance at work. But it can be done. The American Quarter Horse Association traced HYPP, a dominant genetic trait that causes muscles tremors and collapse, to one bulky-built stallion. The International Arabian Horse Association dealt with SCID, a fatal, autosomal recessive condition that leaves foals unable to fight infections, and now has protocols to avoid its transmission. The Rocky Mountain Horse Association tackled ASD, an eye condition, linked to coat color. All it takes is time, money and cooperation. Looking Ahead DISCOVERING whether conformation, cellular components, or other inherited factors influence onset is the first step towards prevention and, hopefully, cure. As with ASD and coat color, or HYPP and body type, DSLD could well be genetically linked to something breeders are selecting for, such as full manes, way of going, or big, brown eyes. As for our four horses at the beginning of the article, all but the second could represent DSLD cases. The stallion with the injured leg more accurately represents arthritis, not DSLD. If he were a DSLD case, eventually both hind legs would become involved. If research is successful, in time, a simple DNA test could take the speculation and delay out of diagnosing DLSD. Classic Symptoms
Common Clues? BECAUSE THE ACTUAL CAUSE IS NOT KNOWN, many things have been considered as possible contributing factors. While these things do not cause DSLD, they may weaken or damage the suspensories, accelerating the wayward healing process.
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