Up to 95% of human allergic reactions to cats are associated to the ‘Fel d1’ allergen. Could Fel d1 blocking of antibodies reduce cat allergies? This in vitro study used two rabbit anti-Fel d1 antibodies already commercially available for an initial assessment, and human sourced plasma IgE from cat allergic, allergic however not allergic to cats, and non-allergics. After a long period of analysis, the most relevant findings from this study indicate that blocking antibodies to Fel d1 could potentially be a novel approach to reduce allergic reactions to cats. Naturally, in vivo studies in subjects allergic to cats, and cats themselves, should be developed before determining clinical benefits of this approach.