Dog ichthyosis a hereditary, monogenic, cornification disorder, appearing early and persisting for life. Cornification disorders form a heterogeneous group of diseases characterised by abnormal differentiation (cornification) of the epidermis. Theichthyoses, a member of this group, are distinguishable clinically by generalised scaling and histopathologically, in most cases, by a thickened stratum corneum. In veterinary medicine, ichthyosis is now commonly classified into either epidermolytic or non-epidermolytic subtypes. Most reported cases in dogs are non-epidermolytic with heterogeneous clinical, histopathological and ultrastructural profiles.