Background: Cat allergens are a major contributor to environmental allergens' overall burden, but efforts to reduce cat allergens are often unsuccessful.

Objective: To determine whether feeding cats a diet containing an egg product with anti-Fel d1 IgY would produce clinically relevant reductions in allergy symptoms of human subjects.

Methods: Following a priming exposure to blankets used for cat bedding, human subjects were subsequently exposed to environmental chambers primed with blankets from cats fed either a control diet or a test diet containing an egg product with polyclonal anti-Fel d1 IgY. 8 cats: 5 neutered male and 3 spayed females were used. Total Nasal Symptom Score and Total Ocular Symptom Score were assessed at regular intervals. Subjects were randomly exposed to the control or test condition on the first exposure and the opposite condition on the second exposure.

Results: The levels of immunologically active Fel d1 in chambers with blankets from cats fed the test diet were lower than those from control cats, and human subjects exposed to this condition showed significantly lower Total Nasal Symptom Scores and improvement in some ocular symptoms.

Conclusion: Fel d1 levels in the environment are significantly decreased by feeding cats a diet containing egg product with polyclonal anti-Fel d1 IgY. This decrease in allergen results in a significant in total nasal symptom scores and some ocular symptoms.

Cat allergy, Fel d1, IgY, Cat dander, allergy, Allergen exposure, Cat