Do commercial dog extracts cross-react with <i>Felis domesticus</i> allergen 1

<b>Background:</b> Half of U.S. households own a dog despite 10% of individuals being sensitized to dog. Assessment and treatment options for dog allergy include the use of commercial dog extracts which have inconsistent performance, making diagnosing and managing dog allergy challenging. Contamination of dog extracts with other allergens has previously been reported. <b>Objective:</b> We sought to determine whether commercial dog extracts contain other aeroallergens. <b>Methods:</b> An extract purity and quantification study on acetone precipitated dog hair and dander extract (AP dog) was performed, 6 aeroallergens; Alternaria (Alt a 1), Ragweed (Amb a 1), German Cockroach (Bla g 2), Dust Mite (Der p t), Cat (Fel d 1), and Rye Grass (Lol p 1). Following, conventional dog hair and dander extract (CV dog) and the new ultrafiltered dog hair and dander extract (UF dog) were also assessed based on the initial results of AP dog. SDS-PAGE was performed on all three dog extracts to compare allergen content. Lastly, serology results and aeroallergen immunotherapy prescriptions were compared. <b>Results:</b> The ELISA trays with Alt a 1, Amb a 1, Bla g 2, Der p 1, and Lol p 1 antibodies did not capture AP dog, while the ELISA tray with Fel d 1 antibody captured AP dog, CV dog, and UF dog. SDS-PAGE results of the 3 dog extracts did not reveal a band at the molecular weight for Fel d 1. <b>Conculsion:</b> Contamination of commercial dog extracts was not found. However, our findings are supportive of commercial dog extracts containing a Fel d 1-like dog allergen that is cross-reactive to Fel d 1. Cross-reactivity between commercial dog extracts and Fel d 1 could be responsible for double positivity to cat and dog in serology. Additional studies are needed to better illustrate this Fel d 1-like dog allergen.