IGHE and urticaria: In horses, allergen hypersensitivity5 leads to cutaneous symptoms, that is eczema6 or urticaria,7 and/or to respiratory symptoms in form of chronic coughing or recurrent airway obstruction (RAO).8, 9 In equine RAO, the exposure to allergens from hay and straw dust and induced symptoms are associated with increased plasma histamine levels10; however, at least in case of the fungus Aspergillus, in vitro IgE diagnosis and intradermal IgE levels do not support IgE‐mediated mechanisms.11 In general, involvement of IgE‐mediated mechanisms in RAO is still controversial.