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Introduction: Tests for dog and cat allergen molecules might be useful to characterize individuals with clinical symptoms in unselected population samples. The aim of this study was to present prevalence data and to investigate airway symptoms to cats and dogs in relation to sensitization to cat and dog allergen molecules.

Methods: In a random sample from a population-based cohort aged 19 years, 595 subjects were tested for sensitization to airborne allergens. Sera from subjects with IgE levels of >0.10 kU/L to cat, dog, or horse were further analyzed by microarray (ImmunoCAP™ ISAC 112) for dog molecules Can f 1–6 and cat molecules Fel d 1, 2, and 4. Fel d 7 was analyzed with ImmunoCAP™. Information about symptoms of asthma and rhinoconjunctivitis upon cat and dog exposure was obtained by a structured interview.

Results: The most prevalent (51.6%) sensitizing dog allergen molecule was Can f 5. The prevalence of asthma upon dog contact increased from 0.9% in individuals negative to all tested dog molecules to 40% in individuals sensitized to 6 dog molecules. The prevalence of asthma upon dog contact was related to the number of dog lipocalin sensitizations independent of sensitization to Can f 5, whereas for rhinoconjunctivitis Can f 5 co-sensitization played a role. The most prevalent (91.2%) sensitizing cat molecule was Fel d 1 and co-sensitization to up to three molecules increased the prevalence of asthma when exposed to cat.

Conclusion: In individuals sensitized to cat as in individuals sensitized to dog, the prevalence of allergic symptoms increased with the number of sensitizing allergen molecules. Individuals sensitized to dog had more complex sensitization patterns to allergen molecules compared to those sensitized to cat. Asthma upon dog exposure was mostly associated with dog lipocalin sensitization, whereas Can f 5 sensitization increased the risk of rhinoconjunctivitis.