Comparison of the results of intradermal testing and aeroallergen‐specific IgE serum testing in dogs with warm weather, seasonal atopic dermatitis

Intradermal testing (IDT) and aeroallergen-specific IgE serum testing (ASIST) are considered important tests for the demonstration of IgE-mediated hypersensitivity in atopic dogs. However, false-positive and negative reactions can occur using either testing method for a variety of reasons. Therefore, the most important criteria used in the diagnosis of atopic dermatitis, i.e. the ‘gold standard’, are the patient's history and clinical findings. Subsequently, IDT and ASIST are primarily used to select aeroallergens for allergen-specific immunotherapy (ASIT). The purpose of this study was to compare the results of IDT and ASIST to the histories of dogs with atopic dermatitis in which there was a very distinct history of a specific warm weather, seasonal pruritus component. Twenty-nine atopic dogs with histories of a warm weather, seasonal pruritus or a year-round pruritus with observable exacerbations during warm weather seasons were included in the study. Dogs with concurrent flea allergy were excluded. For each dog, a 45-aeroallergen intradermal test (IDT) and a 48-aeroallergen-specific IgE immunoassay [Allercept™ Northeast Regional Allergy Screen – (ANRAS)] were performed. In our geographical location, the times for tree, grass, and weed pollination are quite distinct. Dates for pollen levels were obtained from the American Academy of Allergy, Asthma, and Immunology, National Allergy Bureau Counting Stations. Each pollen was reported as follows: tree pollens predominantly in April and May, grass pollens predominantly in June and July, and weed pollens predominantly in August until a killing frost (KF). The histories reported by the 29 dogs’ owners were as follows: seasonal onset or exacerbation of pruritus from April or May until KF in 15 dogs (Group 1), from June or July until KF in nine dogs (Group 2), and from August until KF in five dogs (Group 3). For Group 1, IDT correlated well with positive reactions to tree, grass, and weed pollens in nine of 15 dogs (60%), and ANRAS correlated well in 12 of 15 dogs (80%). When the results of IDT and ANRAS were combined for each dog, the combined results correlated well with the history in 14 of 15 dogs (93%). For Group 2, IDT correlated well with positive reactions to grass and weed pollens in three of nine dogs (33%), and ANRAS correlated well in seven of nine dogs (78%). When the results of IDT and ANRAS were combined for each dog, the combined results correlated well with the history in eight of nine dogs (89%). For Group 3, IDT correlated well with positive reactions to weed pollens in five of five dogs (100%), and ANRAS correlated well in two of five dogs (40%). When the results of IDT and ANRAS were combined for each dog, the combined results correlated well with the history in five of five dogs (100%). In conclusion, IDT correlated well with the history in 17 of 29 dogs (59%) for all groups, ANRAS correlated well in 21 of 29 dogs (72%) for all groups, and combining IDT and ANRAS results correlated well in 27 of 29 dogs (93%) for all groups. The results of this study strongly support the simultaneous use of both IDT and ANRAS for the selection of aeroallergens for ASIT in dogs with atopic dermatitis. Funding: Michigan State University Dermatology Research Account.