Hereditary Equine Regional Dermal Asthenia
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Hereditary Equine Regional Dermal Asthenia (HERDA) aka hyperelastosis cutis (HC) is an inherited autosomal recessive connective tissue disorder. Affected horses have extremely fragile skin that tears easily and exhibits impaired healing. In horses with HC, the skin separates between the deep and superficial dermis. There is no cure. Most individuals receive an injury they can not heal, and are put down. A DNA test for carrier identification is not yet available, and therefore, managed breeding strategy is currently the only option for reducing the incidence of HC.
The disease is found primarily in American Quarter Horses, specifically in cutting horse lines. Most affected horses have been found to trace to Poco Bueno. Some western pleasure lines are affected as well. Other breeds affected are the American Paint Horse Association (APHA), and the Appaloosa Horse Club (ApHC) and any other breed registry that allows out crossing to AQHA horses.
HERDA is characterized by abnormal skin along the back that tears easily and heals into disfiguring scars. The skin is loose, and hyper-elastic in affected horses. Symptoms typically don’t appear until the horse is subjected to pressure or injury on their back, neck or hips, usually around 2 yrs of age. However foals can show signs when injured, while other horses mature and only show signs in the joints. The expression of HERDA is variable, and the phenotypic range of expression is still being determined.
More information about HERDA/HC can be found at www.pubmed.com or at www.thehorse.com see also Poco Bueno.
