Comparison of the results of intradermal test reactivity and serum allergen‐specific I g E measurement for M alassezia pachydermatis in atopic dogs

Background M alassezia pachydermatis is part of the normal flora of canine skin. M alassezia hypersensitivity is recognized as a trigger for clinical signs of atopic dermatitis ( AD ) in some dogs. Determinations of M alassezia 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‐ M alassezia I g E . Animals Eighty‐four dogs with a clinical diagnosis of AD . Methods Multi‐allergen IDT was performed on all dogs. Serum testing for allergen‐specific I g E against a panel of common environmental allergens and M . pachydermatis was performed by ELISA using the Fcε RI α 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‐ M alassezia 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‐ M alassezia 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‐ M alassezia I g E as detected by the Fcε RI α receptor reagent. Although correlation with a clinical diagnosis of M alassezia 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 .