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Less Common
OTHER DIAGNOSES CONSIDERED
Other conditions or ailments that might also need to be ruled out by a vet.
Diagnosis
Conditions or ailments that are the cause of a problem that you see - your observation.
Your vet may diagnose
Hereditary Equine Regional Dermal Asthenia, HERDA
Synonyms: Hyperelastosis Cutis
Summary
This is a heritable (genetic) skin disease seen in certain lines of American Quarter Horses and related breeds, and very rarely in other breeds. Most horses with the classic disease are related somewhere in their pedigree to Poco Bueno, the famous Quarter Horse sire. Cases of HERDA range from mild to severe.
HERDA is a disorder of connective tissue throughout the body, but is most obviously seen in the skin. Connective tissue becomes elastic and weak. It appears as overly stretchy skin usually noticed over the body and back, and particularly under the mane. The skin may tear easily, causing wounds to mysteriously appear.
Unexplainable wounds to the back develop after a horse with HERDA is placed under saddle. For this reason, they cannot be ridden. When pinched, the skin remains tented. Poor elastic recoil causes it to remain in tented ridges for longer than usual.
Genetic testing is being done to eliminate affected horses from the gene pool and definitive diagnosis requires the genetic test on a hair sample. The disease is caused by an autosomal recessive gene. This means that in order for a horse to show signs of disease, it must have gotten a copy of the gene from each parent. It must have two copies of the gene.
HERDA is a disorder of connective tissue throughout the body, but is most obviously seen in the skin. Connective tissue becomes elastic and weak. It appears as overly stretchy skin usually noticed over the body and back, and particularly under the mane. The skin may tear easily, causing wounds to mysteriously appear.
Unexplainable wounds to the back develop after a horse with HERDA is placed under saddle. For this reason, they cannot be ridden. When pinched, the skin remains tented. Poor elastic recoil causes it to remain in tented ridges for longer than usual.
Genetic testing is being done to eliminate affected horses from the gene pool and definitive diagnosis requires the genetic test on a hair sample. The disease is caused by an autosomal recessive gene. This means that in order for a horse to show signs of disease, it must have gotten a copy of the gene from each parent. It must have two copies of the gene.
my vet's role
Diagnostics Used
These are tests that might be helpful to make this diagnosis or further characterize the condition.
Treatments May Include
These treatments might be used to help resolve or improve this condition.
PROGNOSIS AND RELEVANT FACTORS
Prognosis is poor for severely affected horses. Depends on severity of disease.For horses diagnosed with HERDA, new research suggests limiting their exposure to sunlight may help.
my role
I might observe
You might make these observations when a horse has this condition.
Skills I Might Need
I might need these skills if my horse has this diagnosis.
Questions To Ask Your Vet:
- Can I continue to use my horse for breeding if it has this condition or if it is a known carrier?
- How severely affected is my horse?
- What changes in my expectations and management are needed to care for my horse long-term?
Prevention
Remove horses with the condition from the breeding population. DNA test horses with Poco Bueno anywhere in their lineage. This requires a test on a hair sample submitted to a genetics laboratory.
further reading & resources
Helpful Terms and Topics
Written, reviewed or shared by experts in equine health
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Related References:
Rashmir-Raven, A., Lavagnino, M., Sedlak, A., Gardner, K. and Arnoczky, S. (2015), Increased susceptibility of skin from HERDA (Hereditary Equine Regional Dermal Asthenia)-affected horses to bacterial collagenase degradation: a potential contributing factor to the clinical signs of HERDA. Vet Dermatology, 26: 476–e111. doi: 10.1111/vde.12256.