Ichthyosis is a rare skin condition seen in both dogs and cats. One of the so-called "scaling" (or "keratinization") disorders characterized by an abnormality of the top layer of the skin, this disease is inherited as an autosomal recessive trait. It's referred to by the unsavory moniker of "fish scale" disease due to its near-accurate description of the condition.
A variety of versions of ichthyosis are said to exist. These tend to vary by breed. Each form of the disease may take on different patterns in terms of progression of symptoms and location of lesions.
Symptoms and Identification
Affected animals (dogs, primarily) suffer a thickening of the skin. Rough skin under a greasy, scaly haircoat is typical of ichthyosis. Some severely affected animals can experience painful swelling of the footpads, in particular.
Animals are born with this condition and experience a worsening of symptoms with age. In West Highland White terriers, for example, dogs are born with black skin that cracks and peels within two weeks of life.
Diagnosis is achieved via history, signalment, clinical signs, basic skin testing (scrapings, impression smears, etc.) and skin biopsy.
The West Highland White Terrier and the Golden Retriever are the breeds most predisposed to this disease. It has also been described in the:
Treatment is undertaken symptomatically. Supplements (oral fatty acids, for example), medicated shampoos, topical phytosphingosine and propylene glycol sprays, among other approaches. In some isolated instances, glucocorticoids and oral cyclosporine have been used with success to alleviate symptoms somewhat.
Ultimately, however, this disease is considered highly untreatable.
The cost of diagnosis and treatment tends to remain low for most cases due to the inability of even the most expensive drugs to improve an ichthyosis-affected pet's condition. $30 to $50 in shampoos and other topicals comprise the typical monthly expense for this condition. Oral antimicrobials to treat secondary skin infections may sometimes be necessary. In these cases, another $20 to $100 every month may be factored into the expense.
All affected dogs and their first-degree relatives should not be included in breeding programs. Apart from this basic concession, there is no other known means of prevention.
Kwochka, K. W. (1993). Keratinization Abnormalities: Understanding the mechanism of scale formation. Advances in Veterinary Dermatology V2. P. J. Ihrke, I. S. Mason and S. D. White. New York, Pergamon Press. 2: 91-111.
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Lewis, D. T., L. M. Messinger, et al. (1998). "A Hereditary Disorder of Cornification and Multiple Congenital Defects in Five Rottweiler Dogs." Vet Dermatol 9(1): 61-72.
Marsh, K., F. Ruedisueli, et al. (2000). "Effects of zinc and linoleic acid supplementation on the skin and coat quality of dogs receiving a complete and balanced diet." Vet Dermatol 11(4): 277-284.
Mauldin, E., K. Credille, et al. (2007). Clinical, histopathologic and ultrastructural analysis of golden retriever ichthyosis. Nt Am Vet Derm Forum, Kauai.
Mecklenburg, L., U. Hetzel, et al. (2000). "Epidermolytic ichthyosis in a dog: clinical, histopathological, immunohistochemical and ultrastructural findings." J Comp Pathol 122(4): 307-311.