More than half of the world is estimated to have a pet at home. Most of them are cats and dogs. Around 10 – 20 % of the world population is – in higher or lesser extend – allergic to them. Unlike what most people think, it’s not the pets fur what causes the allergic reaction. Most people are allergic to the dander (skin flakes), the urine or the saliva. In allergy-prone individuals, their immune system reacts to allergenic proteins by generation of IgE antibodies, a process called sensitization. These antibodies will bind to receptors on mast cells and basophils, the effector cells of allergic diseases. If a cat or dog-sensitized person then gets exposed to the dander, these effector cells release various mediators such as histamine. These mediators together are at the basis of starting off the allergic symptoms. At Citeq Biologics we have developed cat and dog dander extract for research purposes.