Parakeratosis is an abnormality of the horny layer of the skin leading to a disturbance in the process of keratinization and characterized by extensive crusting of the skin. Lesions are first noted between 6 and 12 months of age. They consist of grayish or brownish crusting. In more severe cases, fissures and erosions may develop. Some dogs experience depigmentation of the remaining nasal planum. The dermatitis does not appear to be worsened by UV light exposure. Improvement of the lesions may be obtained with topical vitamin E, petrolatum and propylene glycol.2 A tendency to generalized or extensive parakeratosis suggests a systemic metaboic disturbance. The classic example is zinc-reponsive dermatosis in pigs and dogs. Normal keratinization has a high requirement for zinc, and a dietary deficiency or imbalance can lead to extensive parakeratotic crusting of the skin. Parakeratosis is also a feature of vitamin A inadequacy or extensive parasitic infestation such as sarcoptic mange. Congenital keratinization defect (congenital follicular parakeratosis; CFP) has been described in the Rottweiler and Siberian Husky. Hereditary nasal parakeratosis of the Labrador Retriever (HNPLR) is a rare condition affecting young dogs. An autosomal recessive mode of inheritance is suspected.
- Senter DA, Scott DW, Miller WH Jr, Erb HN. Intracorneal vacuoles in skin diseases 'with parakeratotic hyperkeratosis in the dog: a retrospective light-microscopy study of '111 cases (1973-2000). Vet Dermatol. 2002 Feb;13(1):43-7
- Rod A. W. Rosychuk, DVM, DACVIM. Dermatology. Canine and Feline Dermatology - an 'Update. April 2005. Colorado State University