Comparison of the results of intradermal test reactivity and serum allergen-specific IgE measurement for Malassezia pachydermatis in atopic dogs

Background Malassezia pachydermatis is part of the normal flora of canine skin. Malassezia hypersensitivity is recognized as a trigger for clinical signs of atopic dermatitis (AD) in some dogs. Determinations of Malassezia hypersensitivity are often made with intradermal testing (IDT), which may have limited availability in a first‐opinion veterinary practice. Hypothesis/Objectives The purpose of this study was to compare immediate IDT reactivity to M. pachydermatis with results of an enzyme‐linked immunosorbent assay (ELISA) designed to detect anti‐Malassezia IgE. Animals Eighty‐four dogs with a clinical diagnosis of AD. Methods Multi‐allergen IDT was performed on all dogs. Serum testing for allergen‐specific IgE against a panel of common environmental allergens and M. pachydermatis was performed by ELISA using the FcεRIα receptor fragment as a detection reagent, with results reported as adjusted optical density (OD). A receiver operating characteristic (ROC) curve was used to analyse the results of the two tests. Results The median adjusted OD of the anti‐Malassezia IgE ELISA for dogs reactive and nonreactive to M. pachydermatis on IDT was 0.137 and 0.024, respectively. Analysis of the ROC curve suggested a cut‐off point for the anti‐Malassezia ELISA that yielded a sensitivity of 77.0% and a specificity of 89% relative to IDT results. Conclusions and clinical importance Substantial agreement was demonstrated between IDT reactivity and anti‐Malassezia IgE as detected by the FcεRIα receptor reagent. Although correlation with a clinical diagnosis of Malassezia dermatitis was not attempted in this study, the results indicate that the ELISA may be used to demonstrate the presence of immediate‐type Malassezia hypersensitivity in dogs with AD. Résumé Contexte Malassezia pachydermatis fait partie de la flore normale de la peau du chien. L'hypersensibilité à Malassezia est reconnue comme un facteur aggravant des signes cliniques de dermatite atopique (AD) chez certains chiens. La détermination de l'hypersensibilité à Malassezia est souvent faite par tests intradermiques (IDT) qui sont peu disponibles en pratique vétérinaire générale. Hypothèses/Objectifs Le but de cette étude était de comparer la réactivité immédiate des IDT à M. pachydermatis avce les résultats d'un test ELISA (enzyme‐linked immunosorbent assay) conçu pour détecter les IgE anti‐Malassezia. Sujets Quatre vingt quatre chiens atopiques. Méthodes Des IDT de plusieurs allergènes ont été réalisées sur