Palmoplantar hyperkeratosis in Irish terriers: evidence of autosomal recessive inheritance

An abnormal development of the epidermis of the footpad was observed in Iri sh terriers. At the age of six months, the affected animals developed smoot h parchment-like footpads. The pad epidermis then hardened and grew lateral cone-like protrusions of up to 5 mm in diameter. Fissures and cracks devel oped and these predisposed the animal to secondary infection. The repeated occurrence in subsequent generations led to the assumption of a hereditary form of hyperkeratosis. Evidence for an autosomal recessive mode of inherit ance was derived from a retrospective analysis of the breeder's records. Th e clinical, histopathological and ultrastructural features of the disease a re presented and the genetic transmission and its implications discussed.