The upper epidermis of atopic dogs is altered at the functional and structural levels.

Abstract

The pathogenesis of human atopic dermatitis (AD) is complex. Like humans, dogs develop spontaneous AD so this species could be a useful model of study. However, AD has been less characterised in dogs than in humans. To compare the epidermis of normal and spontaneously atopic dogs at the functional and structural levels. Six healthy and five atopic laboratory Beagle dogs. Dogs were clinically characterised by general examination, Canine Atopic Dermatitis Extent and Severity Index, 4th iteration (CADESI-04) evaluation and trans-epidermal water loss (TWEL) measurement. Skin biopsies were taken from healthy skin from normal dogs and on nonlesional and lesional skin from atopic dogs. Samples were analysed using transmission electron microscopy (TEM). Cornified envelopes were extracted and examined for their visual aspects (smooth versus ruffled). CADESI-04 and TWEL were significantly higher in atopic dogs. Healthy and nonlesional skin could be distinguished from lesional skin by histopathological evaluation. TEM examination revealed abnormal morphology of the stratum corneum (SC) in atopic skin. The SC compactum corneocyte layer was larger. Thicker and wrinkled corneocytes were more prominent (P = 0.005) in the lesional skin. Similar changes were observed in the nonlesional skin, but less pronounced. The proportion of immature ruffled envelopes was increased in atopic samples (P < 0.05), both from lesional and nonlesional areas. The morphology of the SC was altered in the lesional and apparently nonlesional skin of spontaneously atopic dogs.