title: Are transepidermal water loss and clinical signs correlated in canine atopic dermatitis? A compilation of studies.
abstract: BACKGROUND
  Cutaneous impairment plays a crucial role in atopic dermatitis (AD). Transepidermal water loss (TEWL) measurement is an indirect assessment of skin barrier function and correlates with disease severity in humans. Skin impairment also exists in canine AD; however, concerns exist regarding variability and reliability of TEWL measurements in dogs.
  
  
  OBJECTIVE
  The purposes of this retrospective study were twofold: first, to investigate the correlation between severity of dermatitis [measured by Canine Atopic Dermatitis Extent and Severity Index (CADESI)] and TEWL; and second, to evaluate whether increased TEWL at a young age correlates with disease severity later in life.
  
  
  METHODS
  Data from atopic beagles and dogs with natural AD were analysed. Transepidermal water loss was measured in atopic beagles (n=24) with an open chamber and in dogs with naturally occurring AD with a closed chamber device (two studies, with n=14 and n=18). Pearson product-moment correlation was used for analyses. Transepidermal water loss of the inguinal region, axilla, antebrachial flexure and pinna was analysed. Correlations were investigated for each study, separately first and then jointly. They included CADESI and TEWL of individual regions, total CADESI and total TEWL of all measured regions, and total CADESI and TEWL of key regions.
  
  
  RESULTS
  In atopic beagles, TEWL measured at 1 year of age pre- and post-allergen challenge was correlated with CADESI at 1, 3 and 6 years of age. Overall, low correlation coefficients were found; therefore, a biologically relevant connection could not be demonstrated. The main significant positive correlation was found between TEWL in the pinna and total CADESI.
  
  
  CONCLUSIONS
  It is concluded that TEWL does not correlate with disease severity.
authors.affiliation: Department of Small Animal Clinical Sciences, University of Florida, Gainesville, FL, USA. marsella@ufl.edu
authors.forename: Rosanna
authors.initials: R
authors.lastname: Marsella
mesh_terms: D000818:Animals; D003876:Dermatitis, Atopic / Q000473:pathology / Q000503:physiopathology / Q000662:veterinary*; D004283:Dog Diseases / Q000473:pathology / Q000503:physiopathology*; D004285:Dogs; D012189:Retrospective Studies; D012867:Skin / Q000473:pathology / Q000503:physiopathology; D014870:Water Loss, Insensible / Q000502:physiology*