Ichthyosis and hereditary cornification disorders in dogs

Abstract

The stratum corneum (SC), the outermost layer of the epidermis, serves a crucial role in maintaining body hydration and protection from environmental insults. When the stratum corneum is injured or when the genetic blueprints are flawed, the body is at risk of dehydration, secondary infections and allergen sensitization. Advancements in veterinary dermatology have revealed a wide gamut of disease from relatively benign to lethal that specifically arise from flawed structural proteins, enzymes or lipids needed to create the corneocytes and lipid bilayers of the SC. Some conditions closely mimic their human counterparts while others are unique to the dog. This review will focus on forms of ichthyosis in the dog.

Epidermal barrier dysregulation in atopic skin predisposes for excessive growth of the allergy-associated yeastMalassezia

“…That a dysregulation of the skin barrier establishes a favorable skin environment for Malassezia is supported by Malassezia overgrowth in canine AD 92–94 and hereditary ichthyosis 95 . In further support of the causal relationship between loss of barrier integrity and enhanced fungal control, a case report found topical treatment improving the skin barrier function to coincide with a reduction in the fungal load.…”

“…91 The pro-inflammatory role of SAP1 in Malassezia pathogenicity was confirmed by means of a gene deficient mutant in M. furfur that was impaired in driving inflammation in barrier disrupted skin. 91 That a dysregulation of the skin barrier establishes a favorable skin environment for Malassezia is supported by Malassezia overgrowth in canine AD [92][93][94] and hereditary ichthyosis 95 . In further support of the causal relationship between loss of barrier integrity and enhanced fungal control, a case report found topical treatment improving the skin barrier function to coincide with a reduction in the fungal load.…”

SDR9C7 missense variant in a Chihuahua with non‐epidermolytic ichthyosis

“…Various forms of ichthyosis have primary causes associated with skin barrier function (Akiyama, 2017; Akiyama & Shimizu, 2008; Oji et al, 2010). The skin barrier is fundamental for protection from environmental insults and maintaining body hydration (Mauldin & Elias, 2021). During epidermal terminal differentiation transglutaminases crosslink protein products (e.g.…”

Novel peeling skin condition in neonatal Pacific walruses, Saint Lawrence Island, Alaska, USA

“…This newly observed abnormal skin condition in walrus calves, clinically characterized by peeling skin and cleft formation within the epidermis, most closely resembles ichthyosis, a rare congenital keratin formation defect reported in humans, domestic animals, and other species. 1,14,18 Inherited ichthyosis is usually apparent during the first year of life, often at birth, and continues to affect animals throughout life. The keratin-10 ( K10 ) gene codes for keratin production in the outer layer of the skin; defects in this gene are known to produce skin conditions in humans, such as epidermolytic hyperkeratosis (characterized by thick, blistering skin), ichthyosis with confetti (red, scaly skin), and cyclic ichthyosis (thick, blistering skin).…”

“…The clinical presentation of epidermal skin peeling, with and without intraepidermal cleft formation, and the histopathologic findings of orthokeratotic hyperkeratosis in both calves are compatible with ichthyosis. 14,21 The early onset suggests a congenital form of ichthyosis. Case 2 was found dead.…”