Scientific research has scored another significant victory in the equine world. Two DNA tests are now available to detect carrier status for hereditary equine regional dermal asthenia (HERDA), also known as hyperelastosis cutis (HC).
Today horse owners desiring to know whether they own a carrier mare, stallion, or foal can have it tested at either the University of California Davis or Cornell University in New York, where tests have been developed independent of each other. The cost per individual horse at each institution is $50. Hair follicles provide DNA for the respective tests.
HERDA is a skin disease that is almost always fatal and has been traced back in large part to the Poco Bueno bloodline in Quarter Horses. It is primarily found in the performance and pleasure lines, especially cutting, and seldom shows up in racing or halter horses.
When a horse is afflicted with HERDA, there is a lack of adhesion within the dermis, the deep layer of skin, due, perhaps, to a collagen defect. One can think of it like glue holding the skin layers together. However, with HERDA or HC, the glue is inferior. Because the layers are not held firmly together, they separate. When the horse is ridden under saddle or suffers trauma to the skin, the outer layer often splits or separates from the deeper layer, or it can tear off completely. The wound might heal, but often with disfiguring scars. New damaged areas arise continuously, sometimes even without obvious trauma.
The disease often manifests itself at about a year and one-half of age, but can show up earlier.
The gene implicated in HERDA is autosomal recessive. This means that both sire and dam must have the gene in order for it to be expressed in the offspring.
Two researchers who have been heavily involved in research to develop a genetic test to detect carrier status are Nena Winand, DVM, PhD, research scientist, Department of Molecular Medicine, Cornell University, an