CHARACTERIZATION AND MANAGEMENT OF A JACK-RUSSELL TERRIER WITH CONGENITAL ICHTHYOSIS

A prospective clinical trial was carried out in a 6-week-old male Jack Russell terrier with congenital ichthyosis to evaluate stratum corneu m lipids; transmission electron microscopy of skin specimens; and clin ical and dermatopathological response to vitamin A alcohol therapy. Al so evaluated were the clinical, dermatopathological, and epidermal cel l proliferation kinetics response to a synthetic retinoid in a dog wit h congenital ichthyosis. Epidermal cell renewal time was markedly decr eased compared with normal and seborrhoeic dogs. Skin specimens were c haracterized by severe and diffuse compact orthokeratosis that extende d into the infundibulum of the hair follicles. The stratum granulosum was normal. On transmission electron microscopy, the stratum corneum w as thickened and intercorneocyte spaces were extremely narrow. The fir st three corneocyte layers contained tonofilaments that were irregular , coarse and wavy. Tonofilament packing appeared more normal and regul ar in the fourth and fifth corneocyte layers. Outer layers of stratum corneum were extraordinarily electron-dense compared with normal. Ther e was a decrease in stratum corneum free fatty acid and acyl-ceramide and an increase in ceramide III levels compared with three normal dogs . Three months of oral vitamin A alcohol did not result in clinical im provement, although histologically the orthokeratosis was less compact . After 6 months of oral etretinate therapy, comedones and scales were markedly less evident grossly. Although compact orthokeratosis was st ill present on histological examination of skin, it was less than that present at 6 weeks of age. Epidermal cell kinetics were not altered a fter etretinate therapy.