Herda

Clear

Good news!   

Your horse is clear of hereditary equine regional dermal asthenia and does not have this gene mutation.   

Your horse cannot pass on this mutation. There are no breeding or performance implications.  

What is hereditary equine dermal asthenia?

Hereditary equine dermal asthenia symptoms often appear in horses when their training under saddle starts. Affected horses develop skin lesions after the saddle is introduced when the skin tears and leaves open lesions over the horse’s back.  

Occasionally horses with mild symptoms can be lightly ridden or kept as paddock companions. Unfortunately, because of the gravity of this disease, most horses are euthanized soon after the diagnosis.

Genomic Details

Hereditary equine regional dermal asthenia (HERDA) is caused by a mutation in the PPIB gene that is on chromosome 1. This gene is involved in the formation of collagen needed for connective tissue in the horse’s body, such as the skin and tendons, as well as the eyes and heart. Without proper collagen formation skin starts to separate.

The mutation that causes hereditary equine regional dermal asthenia (HERDA) is a switch in one of the four base pairs that make up a DNA molecule. Guanine (G) is replaced by Adenine (A) changing the PPIB gene. Therefore, a horse’s genetic result for hereditary equine regional dermal asthenia is one of three possibilities:

  • G/G: Normal. Does not have the disease. Does not have the mutation.

  • G/A: Carrier. Does not have the disease. Carries one gene mutation from one parent. This might be passed to their foal.

  • A/A: Affected. Has the genetic disease. The horse has inherited a gene mutation from each parent. One mutation will be passed to their foal.