Elevated cortisol content in dog hair with atopic dermatitis.

Canine atopic dermatitis (CAD) is a chronic relapsing inflammatory skin disease occurring in 10% of the canine population. Although most studies have focused on the pathophysiological mechanism involved in CAD, the detrimental impact of CAD on quality of life has received only little attention. Hair cortisol analysis is becoming a valuable tool in monitoring chronic stress. To further validate this approach in CAD, we compared the hair cortisol concentration of atopic dogs with that of healthy conditioned dogs. The extent and severity of cutaneous lesions of atopic dermatitis were assessed according to modified CADESI-03 scores. In addition, skin barrier function was evaluated by measuring transepidermal water loss (TEWL) and stratum corneum conductance. The correlation between CAD severity and hair cortisol concentration was evaluated. The level of hair cortisol evaluated by ELISA assay showed that the atopic dermatitis group had significantly increased cortisol levels compared to that of the healthy control group. A significant positive correlation was identified between hair cortisol level and the CADESI score in CAD patients. The TEWL value of the cubital flexor of the forelimb in the atopic group was significantly higher compared to the healthy controls. These findings imply that the hair cortisol analysis can be an effective and objective biomarker in assessment of long-term stress of CAD patients.