Correlation between transepidermal water loss (TEWL) and severity of clinical symptoms in cats with atopic dermatitis

The aim of this study was to demonstrate whether there is a correlation between transepidermal water loss (TEWL) and the severity of skin lesions in cats with feline atopic dermatitis (AD). The severity of symptoms was determined by using 2 scoring systems for clinically assessing the skin lesions in cats: Scoring Feline Allergic Dermatitis (SCORFAD) and Feline Extent and Severity Index (FeDESI). Such a correlation between TEWL and systems for clinically evaluating symptoms has already been shown in humans and dogs. Measurements were taken in 18 European Shorthair cats: 11 females and 7 males. Scores were calculated using SCORFAD and FeDESI and TEWL was measured in 7 areas of the body. Correlations were calculated between SCORFAD and TEWL and between FeDESI and TEWL for each body region and the average TEWL was also calculated with each system. Positive correlations were found between SCORFAD and TEWL in 3 of the examined areas: thorax (r = 0.44, P = 0.02); axilla (r = 0.39, P = 0.04); and forelimb (r = 0.55, P = 0.02). A correlation was also found between the average TEWL and SCORFAD (r = 0.41, P = 0.03). In the case of FeDESI, a correlation was found in the forelimb (r = 0.53, P = 0.02), but no correlation was found between FeDESI and the average TEWL. The results obtained showed that TEWL can be used as an additional tool in clinically assessing atopic dermatitis in cats, although it seems to be less useful in cats than in humans.