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J Feline Med Surg. 2019 Oct;21(10):875-881. doi: 10.1177/1098612X19861218. Epub 2019 Jul 16.

Anti-Fel d1 immunoglobulin Y antibody-containing egg ingredient lowers allergen levels in cat saliva.

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Research & Development, Nestlé Purina Research, St Louis, MO, USA.



Fel d1 is the major cat allergen, causing IgE reactions in up to 90% of cat-allergic adults. Fel d1 secreted in saliva is spread to the haircoat during grooming. Current management includes attempts to reduce or eliminate exposure to Fel d1. A novel approach to reducing immunologically active Fel d1 (aFel d1) exposure, which involves binding the Fel d1 with an anti-Fel d1-specific polyclonal egg IgY antibody (sIgY), was evaluated. The hypothesis was that saliva from cats fed diets containing this sIgY would show a significant reduction in aFel d1.


Two trials in cats were completed. In trial 1, saliva was collected 0, 1, 3 and 5 h post-feeding during a 2 week baseline and subsequent 6 week treatment period. Trial 2 included a control and treatment group, and saliva was collected once daily. Trial 2 cats were fed the control diet during a 1 week baseline period, and then fed either control or sIgY diet during the 4 week treatment period. Fel d1-specific ELISA was used to measure salivary aFel d1. Data were analysed using repeated-measures ANOVA and a linear mixed-model analysis.


Salivary aFel d1 decreased post-treatment in both trials. There were no differences in aFel d1 based on time of collection relative to feeding in trial 1. In trial 2, 82% of treatment group cats showed a decrease in aFel d1 of at least 20% from baseline vs just 38% of control cats. Only one (9%) treatment cat showed an increase in aFel d1 vs 63% of control cats.


Feeding sIgY significantly reduced aFel d1 in the saliva of cats within 3 weeks. Although additional research is needed, these findings show promise for an alternative approach to the management of allergies to cats.


Fel d1; Human allergy; allergen; allergies to cats; chicken IgY; diet


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