Effects of a lipid mixture on glucocorticoid-induced barrier impairment and epidermal atrophy in the canine skin

The aims of the present study were to characterize the effect of glucocorticosteroids (GCs) on the normalcanine skin and to evaluate the effect of a lipid mixture (LM), containing cholesterol, pseudoceramide, and free fattyacid, on the steroid-induced damaged skin of dogs. Five beagles were involved and the skin of the back of each dogwas topically applied with four kinds of GCs twice daily for 28 days. LM was applied after that period of GCsapplication. Transepidermal water loss (TEWL), skin hydration, and skin pH were assessed during experimental periodsand histopathological evaluation was performed. TEWL was significantly increased, with a maximum increase obtainedon day 28 (p < 0.01). Skin pH was significantly decreased, with a maximum decrease obtained on day 28 (p < 0.01).Skin surface hydration was significantly increased on day 3, but values of skin hydration were progressively decreasedand finally reached those of baseline. In histology, as results of steroid application, losses of keratin layers in thestratum corneum and edematous changes in the upper parts of dermis, and consequently, thickness of the epidermisand the stratum corneum were decreased. In addition, the numbers of hair follicles were markedly decreased in steroidcontrol as compared to intact control. However, these skin atrophic changes were markedly inhibited by treatment ofLM as compared with steroid control in the present study. Moreover, all biophysical parameters were reached to thebaseline after LM treatment. These results showed that the topically applied GCs induced skin barrier impairment anda LM should be effective on repair of disturbed skin barrier function in dogs. Therefore, it is concluded that a LMtested in the present study is expected to treat the steroid-induced skin damages.