Seasonality of Serum Allergen-Specific IgE Levels in Scandinavian Dogs Suspected of Allergy

Canine atopic dermatitis (AD) is a common allergic skin disease for which identifying allergen sensitization via IgE serological or intradermal testing is necessary to implement allergen-specific immunotherapy. Because serum IgE has a short half-life and circulating levels fluctuate with environmental allergen exposure, the timing of blood sampling may influence serological test outcomes. This cross-sectional study assessed seasonal variation in allergen-specific IgE concentrations and seropositivity rates across pollen and mite allergen categories in Scandinavian dogs suspected of allergic disease. PAX multiplex macroarray results from 5014 canine sera submitted by veterinarians across Denmark, Norway, and Sweden over one full year were retrospectively analyzed for 17 allergens, including tree, grass, and weed pollens, house dust mites, and storage mites. Mean sIgE levels showed statistically significant but relatively small seasonal variation. Seropositivity rates, however, showed clearer patterns: seropositivity for tree and weed pollen was highest in spring and summer, and that for house dust mite peaked in autumn and winter, while storage mite sensitization rates showed the opposite trend. These results confirm that IgE serological test results in dogs are affected by the sampling season and emphasize the importance of considering timing when collecting and interpreting IgE serological tests in atopic dogs.