Allergen-specific immunotherapy (ASIT; injection or drops) is a common treatment modality for canine atopic dermatitis with therapy recommendations based on in vivo (intradermal), in vitro (serum allergen), or a combination testing. Sera from 10 dogs diagnosed with atopic dermatitis were collected; samples were divided into 4 equal aliquots with each aliquot submitted to 1 of 4 commercial laboratories for allergen-specific IgE assay. Although the testing methodology was similar (ELISA), each testing protocol differed with binding of canine IgE in their assays. The overall diagnostic agreement across all dogs and laboratories was slight when corrected for chance. The diagnostic agreement by dog and laboratory pair was also slight for most comparisons. There was slight agreement for plants and fungi, but substantial agreement for mites. Regarding allergen-
specific therapy recommendations, the overall agreement between laboratories was slight.