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HERDA Hereditary Equine Regional Dermal Asthenia

    Test that shows if your horse carries the gene change that makes the skin on the back weak and easy...

    €43.05 شامل ضريبة القيمة المضافة

      AboutAbout

      This test shows whether your horse carries the gene change behind HERDA, an inherited skin disease. The skin of an affected horse is weak: it stretches, tears and scars, most of all along the back where the saddle sits.

      It is meant for Quarter Horses and horses with Quarter Horse lines, such as Paints, Appaloosas and crosses, before breeding or sale.

      Why test?Why test?

      Breeding. Knowing the result of both parents tells you what each mating can produce. This matters most in cutting horse lines, where the variant is concentrated.

      Studbook and stallion licensing. Several registries now require genetic panel testing of breeding stallions. Check your studbook's current rules.

      Buying and selling. The result is objective information you can show a buyer.

      A young horse with skin problems. If the skin starts to stretch, tear or scar, the result confirms or rules out HERDA. This can spare a horse that does not have it from being put down.

      Clinical signsClinical signs

      Affected foals rarely show anything at birth. Serious skin damage starts on average at about a year and a half and is usually noticed between 18 and 24 months, often when the horse is first broken to saddle. A knock or a rub can bring it out as early as 6 months, and a few horses show nothing until they are four or five.

      • Swellings under the skin, filled with fluid or blood, which owners often call blisters. This is the most common first sign.
      • Loose skin that lifts away easily when pinched and does not spring back
      • Open wounds, skin that comes away from ordinary contact, and wounds that heal badly
      • Disfiguring scars, with thin white hairs where the coat grows back
      • Damage along the back from the withers to the croup, and also over the hindquarters, neck, sides of the chest and belly, lower legs, face, top of the tail and coronary band
      • The skin damage does not itch and is not painful in itself, but large open areas and blood-filled swellings do hurt and change the horse's behaviour
      • Heat and sunlight make it worse; several weeks kept in a stable tend to improve it
      • Ulcers on the surface of the eye, weaker tendons and ligaments in the lower leg and a higher risk of arthritis have also been described
      • Two affected horses have been reported with a skin cancer that spread through the body

      None of these signs is unique to HERDA. Your veterinarian makes the diagnosis, using the history, the examination and this result.

      TransmissionTransmission

      HERDA is recessive. A foal needs one copy from the sire and one from the dam to be affected. The gene is not on a sex chromosome, so colts and fillies are affected equally.

      What each mating can produce:

      • n/n x n/n gives 100% n/n
      • n/n x n/HERDA gives 50% n/n, 50% n/HERDA
      • n/n x HERDA/HERDA gives 100% n/HERDA
      • n/HERDA x n/HERDA gives 25% n/n, 50% n/HERDA, 25% HERDA/HERDA
      • n/HERDA x HERDA/HERDA gives 50% n/HERDA, 50% HERDA/HERDA
      • HERDA/HERDA x HERDA/HERDA gives 100% HERDA/HERDA
      PreventionPrevention

      There is no cure, so prevention is a breeding decision.

      Breeding. Mate a carrier only with a partner that tested negative, and test every foal. No affected foals are born, though some foals will be carriers. This keeps a valuable line while the variant is bred out. Being a carrier is not by itself a reason to stop breeding a horse.

      Managing an affected horse. An affected horse can be kept comfortable, but no treatment restores the skin. Many are put down because they cannot be ridden and should not be bred from. Your veterinarian guides riding, wound care and quality of life.

      ResultsResults

      n/n: negative. No copy of the HERDA variant. Cannot pass it on.

      n/HERDA: carrier. One copy. The horse stays healthy and never develops the disease. Can pass the variant on.

      HERDA/HERDA: affected. Two copies. The horse has the disease and passes the variant to every foal.

      SampleSample

      Hair roots: 20 to 40 hairs pulled (not cut) from the mane or tail, with the roots attached. Tape them inside the marked area of the printable sample submission form. Hairs without roots cannot be analysed.

      Blood: 5 mL of whole blood in a K3-EDTA tube, collected by a veterinarian. Label the tube with the horse's name and send it with the submission form.

      Keep samples dry and at room temperature, and do not freeze them. Do not send hair that is wet, mouldy or soiled with bedding or faeces.

      Send your sample by regular mail or express delivery to:

      Equigerminal Lab HIESE
      Rua da Quinta do Sobreiro Nº25
      3230-343 Penela, Portugal

      TurnaroundTurnaround

      Standard processing: results within 5 to 10 working days of the sample arriving at the laboratory. Shipping is arranged and paid for by the client, and transit time is not included in the 5 to 10 working days.

      Samples that fail DNA extraction or amplification are repeated at no extra cost, which may add a few working days. We contact you if a new sample is required.

      How it worksHow it works

      🛒 Purchase the test: select and buy the test online.

      📧 Receive instructions: after payment confirmation you receive sample collection instructions by e-mail.

      ✨ Collect the sample yourself: pull 20 to 40 hair roots with the bulb attached, or ask your veterinarian to collect blood in a K3-EDTA tube.

      📄 Complete the form: print and complete the submission form with the animal identification.

      📮 Send it to the laboratory: Equigerminal, S.A., HIESE, Rua da Quinta do Sobreiro, 25, Quinta Vale do Espinhal, 3230-343 Penela, PORTUGAL.

      📄 Receive your report: your certified report is issued as soon as the analysis is validated.

      FAQsFAQs

      At what age can a horse be tested?
      Any age, from newborn foal to adult. The genotype never changes, so one test lasts for life.

      Can pedigree tell me instead?
      No. The foundation sires behind the affected lines also appear in the pedigrees of most Quarter Horses that are not carriers. Only the DNA test tells a carrier from a clear horse.

      Does a negative result rule out fragile skin?
      No. This test looks only for HERDA. It does not detect WFFS or other fragile-skin diseases of the horse, which can look alike.

      For ProfessionalsFor Professionals

      Genetic and clinical detail for veterinarians, geneticists and laboratories.

      • Gene / locus: PPIB (peptidylprolyl isomerase B, cyclophilin B), ECA1.
      • Variant: G39R (Gly39Arg), missense. HGVS (EquCab3.0): NC_009144.3:g.129307092G>A; NM_001099761.1:c.115G>A; NP_001093231.1:p.(Gly39Arg).
      • Alternative designations: G6R in Ishikawa et al. (2012), counted from a different starting residue of the protein; both names denote the same change. Disease synonyms: hereditary (heritable) equine regional dermal asthenia, hyperelastosis cutis.
      • Variant identifiers: rs396329681 (EVA); OMIA variant 157.
      • Variant classification: not currently evaluated (ISAG/AVCG, per OMIA).
      • Mechanism: isomerase activity preserved, but cyclophilin B protein interactions and collagen folding are altered, so dermal collagen is abnormal (Ishikawa et al., 2012).
      • Inheritance: autosomal recessive (OMIA code R; Tryon et al., 2005). Generally attributed to a founder effect.
      • Breeds with documented carriers or cases: Quarter Horse (OMIA variant record); affected American Paint Horses and Appaloosas also reported, both registries with Quarter Horse ancestry. Of 58 affected horses, 52 Quarter Horses, 4 Paints, 2 Appaloosas (Tryon et al., 2005); of 50 affected horses, 43 Quarter Horses, 1 Quarter Horse cross, 4 Paints, 2 Appaloosas (White et al., 2004).
      • Allele / carrier frequencies: carrier frequency 3.5% (38 of 1,079 unaffected control Quarter Horses; Tryon et al., 2007). Carrier frequency by discipline about 28% in cutting, 12.8% in western pleasure and 11.5% in working cow horses, and 1.7% in American Paint Horses (Rashmir-Raven, 2013). Carrier frequency 1.6% (2 of 125 Quarter Horses in France, both mares; White and Bourdeau, 2011). Allele frequency 13.5% in elite cutting Quarter Horses, with no change over time in the random cohort (Brown et al., 2026; 300 performance and 300 random horses born 2020 to 2024). Carrier and allele frequencies are not interchangeable; for a rare recessive the allele figure is roughly half the carrier figure.
      • Clinical / diagnostic notes for veterinarians: age at first owner observation ranged from birth to four years in the White et al. (2004) series. None of those 50 horses had joint hyperlaxity or visceral involvement; later work describes joint laxity at birth in some foals, and viscera were normal in the foal and dam followed by White et al. (2007). Corneal thinning has been described. One adult HERDA/HERDA horse was reported working normally with mild signs (Patterson Rosa et al., 2021), so genotype does not predict severity. Skin biopsy is a separate procedure; histopathology is suggestive but not diagnostic, and suspected cases should be confirmed by genotyping. Fragile-skin disease not caused by this variant occurs, including in a Quarter Horse gelding (Steelman et al., 2013).

      Key references:

      • Tryon RC, White SD, Bannasch DL (2007). Homozygosity mapping approach identifies a missense mutation in equine cyclophilin B (PPIB) associated with HERDA in the American Quarter Horse. Genomics 90:93-102. doi:10.1016/j.ygeno.2007.03.009. PMID 17498917.
      • Tryon RC, White SD, Famula TR, Schultheiss PC, Hamar DW, Bannasch DL (2005). Inheritance of hereditary equine regional dermal asthenia in Quarter Horses. Am J Vet Res 66:437-442. doi:10.2460/ajvr.2005.66.437.
      • White SD, Affolter VK, Bannasch DL, Schultheiss PC, Hamar DW, Chapman PL, et al. (2004). Hereditary equine regional dermal asthenia (hyperelastosis cutis) in 50 horses: clinical, histological, immunohistological and ultrastructural findings. Vet Dermatol 15:207-217. doi:10.1111/j.1365-3164.2004.00402.x.
      • Ishikawa Y, Vranka JA, Boudko SP, et al. (2012). Mutation in cyclophilin B that causes hyperelastosis cutis in American Quarter Horse does not affect peptidylprolyl cis-trans isomerase activity but shows altered cyclophilin B-protein interactions and affects collagen folding. J Biol Chem 287:22253-22265. doi:10.1074/jbc.M111.333336.
      • White SD, Bourdeau P (2011). Prevalence of the mutation in cyclophilin B (PPIB), a causal candidate gene for HERDA, among Quarter Horses in France. Vet Dermatol 22:206-208. doi:10.1111/j.1365-3164.2010.00941.x.
      • Rashmir-Raven A (2013). Heritable equine regional dermal asthenia. Vet Clin North Am Equine Pract 29:689-702. doi:10.1016/j.cveq.2013.09.001.
      • Brown BN, Hughes S, Le TM, Tatar NP, Grahn JC, Carrillo-Alvarez M, Bellone RR, Finno CJ (2026). Allele frequencies of 7 inherited disorders in performance and random cohorts of American Quarter Horses (2020-2024). J Am Vet Med Assoc 1-7. doi:10.2460/javma.26.04.0256.

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