According to Dr. Ann Rashmir, DVM, associate professor at Mississippi State University School of Veterinary Medicine, a DNA test developed by Cornell University is now available for horse owners to determine whether an animal is a carrier for the genetic disease hyperelastosis cutis, more widely known as HERDA (hereditary equine regional dermal asthenia).

Dr. Nena Winand, DVM, (pictured) with the Department of Molecular Medicine at Cornell University’s College of Veterinary Medicine, and Rashmir have collaborated since 2004 on research into the disease, most commonly associated with closely related cutting horse bloodlines.

The DNA test, developed to enable breeders to manage the disease for which there is no cure, identifies normal, carrier and affected horses, including newborn foals. It requires either a blood sample or 20 to 30 mane or tail hairs, with roots attached (tail hairs are preferred for neonatal foals). The cost of the test is nominal and results are confidential.

HERDA manifests itself as a collagen defect in the skin, resulting in sores and lesions that heal poorly, if at all, and render horses unrideable. Afflicted horses are usually euthanized because of a poor prognosis.

A homozygous recessive gene causes HERDA. Both parents must carry the gene for offspring to be afflicted. Since carriers are not afflicted with the disease, up until now, it has been difficult to positively identify carriers.

Laws of genetics dictate that there is a 25 percent chance that the offspring of two carriers will develop the disease; that 50 percent will be carriers; and that 25 percent will be normal. When an afflicted horse is crossed with a carrier, the offspring will be either carriers of or afflicted with the disease; and when an afflicted horse is crossed with a normal horse, 100 percent of the offspring will be carriers.

For information about HERDA testing, contact: Nena Winand, DVM, PhD; Cornell University College of Veterinary Medicine; e-mail at