Hyperelastosis cutis

Veterinary advice should be sought before applying any treatment or vaccine.

Hyperelastosis Cutis

HERDA, Hereditary Equine Regional Dermal Asthenia

Hyperelastosis cutis (HC), otherwise known as hereditary equine regional dermal asthenia (HERDA), is a connective tissue skin disorder in Quarter horses. It is an inherited skin defect which causes horses to have abnormally fragile skin, making them more susceptible to injury and to developing slow-healing wounds. HC resembles Ehlers-Danlos syndrome (EDLS) in humans. Horses with HC are typically born normal and start to develop symptoms as they age. Affected foals will often develop seromas, hematomas, and ulcerations on their backs that get progressively worse with age and increase in frequency. Onset is typically associated with initial saddling or trauma. Horses with HC have also shown to have an increased risk of developing corneal ulcers.

HC is caused by a missense mutation in cyclophilin B (Cyp). Cyp is significant in the triple helix folding of collagen. The mutation is homozygous in affected horses.


Excessively fragile skin
Slow-healing wounds
White hairs present at areas of hair re-growth
Sensitivity to touch along the back


  • History
  • Clinical signs
  • Physical exam
  • DNA testing
  • Skin biopsy



There is no effective treatment and horses are usually euthanized; however palliative therapy is available.



Poor, horses are usually euthanized

Scientific Research

General Overviews

  • Loose skin icon
  • herda icon
  • herda icon

Commonly Affected Breeds

Quarter Horse icon