Hereditary Footpad Hyperkeratosis is an inherited disease of footpads affecting Irish terriers. Affected dogs typically present around 4 to 6 months of age with hard, thickened footpads. With time, the abnormal footpads often develop deep cracks predisposing affected dogs to foot infections, significant pain and lameness. Thick, horny growths also commonly develop around the rim of the footpads. Toenails of affected dogs are harder than normal and appear to grow faster. In addition, some affected dogs may display a duller and softer hair coat than normal littermates.
Breed-Specific Information for the Irish Terrier
The Mutation of the FAM83G gene associated with hereditary footpad hyperkeratosis has been identified in Irish terriers. Though the exact frequency in the overall Irish terrier population is unknown, approximately 13% out of 171 Irish terriers tested were carriers of the mutation.
Genetic testing of the FAM83G gene in Irish terriers will reliably determine whether a dog is a genetic Carrier of hereditary footpad hyperkeratosis. Hereditary footpad 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 FAM83G 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. Irish 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.
Drögemüller M, Jagannathan V, Becker D, Drögemüller C, Schelling C, Plassais J, Kaerle C, Dufaure de Citres C, Thomas A, Müller EJ, Welle MM, Roosje P, Leeb T. A mutation in the FAM83G gene in dogs with hereditary footpad hyperkeratosis (HFH). PLoS Genet. 2014 May 15;10(5):e1004370.