Epidermolytic Hyperkeratosis

Common Symptoms

Epidermolytic Hyperkeratosis is an inherited condition of the skin affecting Norfolk Terriers. Affected dogs can display sloughing and blistering of the skin with rubbing as may occur when drying the pups after birth. As the dog matures, the skin becomes flaky and dark (hyperpigmented), especially in locations on the body where two skin areas may touch or rub together. The footpads, claws, teeth and hair of affected dogs are typically normal.

Breed-Specific Information for the Norfolk Terrier

The Mutation of the KRT10 gene associated with epidermolytic hyperkeratosis has been identified in the Norfolk Terrier, although its overall frequency in this breed is unknown.

Testing Tips

Genetic testing of the KRT10 gene in Norfolk Terriers will reliably determine whether a dog is a genetic Carrier of epidermolytic hyperkeratosis. Epidermolytic Hyperkeratosis is inherited in an Autosomal Recessive manner in dogs meaning that they must receive two copies of the mutated gene (one from each parent) to develop the disease. In general, carrier dogs do not have features of the disease but when bred with another carrier of the same Mutation, there is a risk of having affected pups. Each pup that is born to this pairing has a 25% chance of inheriting the disease and a 50% chance of inheriting one copy and being a carrier of the KRT10 gene mutation. Reliable genetic testing is important for determining breeding practices. In order to eliminate this mutation from breeding lines and to avoid the potential of producing affected pups, breeding of known carriers to each other is not recommended. Norfolk Terriers that are not carriers of the mutation have no increased risk of having affected pups.

There may be other causes of this condition in dogs and a normal result does not exclude a different mutation in this gene or any other gene that may result in a similar genetic disease or trait.

References

• Credille KM, Barnhart KF, Minor JS, Dunstan RW. Mild recessive epidermolytic hyperkeratosis associated with a novel keratin 10 donor splice-site mutation in a family of Norfolk terrier dogs. Br J Dermatol. 2005 Jul; 153(1):51-8. [PubMed: 16029326]