Pilot study using five methods to evaluate skin barrier function in healthy dogs and in dogs with atopic dermatitis

Background Atopic dermatitis is associated with skin barrier defects. In people, noninvasive techniques are used to quantify the skin barrier functionality. In dogs, transepidermal water loss (TEWL), stratum corneum hydration and pH have been used to assess skin barrier function. However, few studies have determined their repeatability. Objective To assess the repeatability of measurements of skin hydration, TEWL, pH, skin absorbance and erythema in healthy and atopic dogs. Animals Fifteen healthy and 15 atopic privately owned dogs. Methods and materials Three repeated measurements using Corneometer (R), Skin-pH-Meter (R), Colorimeter (R) and VapoMeter (R) were obtained from inguinal, axilla, pinna and interdigital space by three investigators. Intra- and interobserver variability (coefficient of variation, correlation coefficients and intraclass correlation coefficients) and difference between the two groups (t-test or Mann-Whitney U-test) were determined. Results High repeatability and low variation were observed both intra- and interobservers for all devices except the VapoMeter (R). The most repeatable device was the Skin-pH-Meter (R), whereas the VapoMeter (R) was the device with the highest intra- and interobserver variability. Atopic dogs had a significantly increased pH (inguinal P = 0.03; axilla P = 0.02) and erythema (inguinal P = 0.01; axilla P = 0.02) compared to healthy dogs. No differences between the two groups were detected using the Corneometer (R), VapoMeter (R) or Colorimeter (R) (tartrazine absorption). Conclusion and clinical significance The results of this pilot study support the use of Corneometer (R), Skin-pH-Meter (R) and Colorimeter (R) in the assessment of skin barrier function in dogs; further investigations to optimize measurements and confirm these results are needed.