Hereditary Disorders of Keratinization

Disorders of keratinization lead to hyperkeratosis and occur in specific breeds. The hyperkeratosis may be parakeratotic or orthokeratotic. The epidermis and follicular epithelium may be hyperplastic. The changes in the epidermis and the accumulations of keratin may lead to secondary infections which need to be treated and controlled.
Diagnosis is usually made by ruling out other differential diagnoses and then confirming through histopathology. Biopsies should be obtained from the thickest areas of scaling, moderate scaling areas and relatively normal areas.
Keratinization defects require lifelong management. Treatment of secondary infections (both bacterial and yeast) is very important. Bathing with a shampoo that is keratolytic and keratoplastic and non-drying is very helpful in reducing scale and preventing secondary infections. Systemic therapy with vitamin a (10,000 iu sid to bid or in large breeds as high as 20,000 iu bid) or retinoids may be useful.

Specific disorders
Primary seborrhea
Is an inherited disorder of cornification that has been reported in cocker spaniels, english springer spaniels, bassett hounds, golden retrievers and shar peis, doberman pinschers, irish setters and german shepherd dogs. Seborrhea is clinically described as greasy (oleosa) or dry (sicca). It is extremely important to rule out other causes of excessive scaling such as endocrinopathies, ectoparasites, pyoderma, malassezia dermatitis, demodicosis, leishmaniasis, neoplasia, follicular dysplasias, allergic dermatitis or environmental influences because the majority of seborrheic cases will be secondary. Primary seborrhea should be confirmed through histopathology.
Management of primary seborrhea involves controlling secondary infections, proper grooming to reduce the build up of scale with weekly keratolytic/keratoplastic shampoos and systemic therapy. Oral vitamin a and retinoids have been used to help “normalize” the keratinization process. [...]