Epidermal Dysplasia

Summary

Epidermal dysplasia is one of a number of inherited scaling diseases of the skin that are most often over-simplistically designated as "seborrhea" (a general term for skin dryness). More complex than simple dryness, this is a condition in which the outer layer of the skin (the epidermis) proliferates abnormally and eventually flakes off in large clumps, or scales.

The difference between this disease and other inherited scaling diseases (also referred to as "keratinization disorders"), is its severity, despite its early onset (usually within the first year of life).

Described only in West Highland white terriers, this disease is now understood to be an autosomal recessive trait.

Unfortunately, this disease is not well understood. As such, diverging opinions on its pathophysiology and treatment abound.

Symptoms and Identification

Early on, dogs with epidermal dysplasia will have hyperpigmentation (increased pigment deposition) of the ear flaps (pinnae) and underarms (axillae). Eventually, the skin of the underside (chest and abdomen) tends to be the most severely affected. The limbs, too, will eventually also become hyperpigmented and thickened with redness, scaling and hair loss a constant feature. Intense itchiness is a standard characteristic.

Excessive yeast and bacteria on the skin is always a complicating factor. Indeed, the presence of Malassezia (a kind of yeast) in vast populations is a hallmark of this disease process.

To diagnose epidermal dysplasia, skin biopsies and scrapings are generally undertaken, but history and signalment (breed and age designation) are usually sufficient to identify this disease.

Affected Breeds

The West Highland White Terrier is the only breed described as suffering this specific disease.

Treatment

Though management of this condition is possible, curing it is considered impossible. As such, treatment is undertaken primarily through aggressive antimicrobial therapy by way of controlling the secondary infections caused by the skin abnormality. Topical and oral antibiotics and antifungal drugs are standard fare for this disease. They are offered frequently and often at high doses.

Treating concurrent diseases is critical to the long-term comfort of dogs with this incurable disease. Because allergic skin disease is often a complicating factor in these cases, allergy testing and treatment often becomes a necessary step.

Veterinary Cost

The cost of treating this disease is quite high given the time and expense associated with the drugs, shampoos and topicals required. $100 to $200 every month would not be considered atypical for a severely affected patient. Should allergic skin disease complicate the process, the expenses associated with diagnosis and treatment of this disease would likely increase by $500 to $1,000 a year or more.

Prevention

The primary form of prevention has to do with sterilization of all affected dogs and their first degree relatives.

References

Nett, C. S., I. Reichler, et al. (2001). "Epidermal dysplasia and Malassezia infection in two West Highland White Terrier siblings: an inherited skin disorder or reaction to severe Malassezia infection?" Vet Dermatol 12(5): 285-90.

Scott, D. W., W. H. Miller, Jr,, et al. (2001). Muller and Kirk's Small Animal Dermatology. Philadelphia, W,B. Saunders.

Scott, D. W. and W. H. Miller, Jr. (1989). "Epidermal dysplasia and Malassezia pachydermatis infection in West Highland White terriers." Vet Dermatol 1: 25-36.