Cat Allergies

By Pierre P. Gagnon, MD

Pierre-Paul Gagnon, MD

More Allergy, Asthma & Infectious Disease Articles

Cat Allergies

Allergic response inhalant allergies can affect the nose, the eyes, and the chest (asthma). Allergic rhinitis can occur on a seasonal basis or year round. A typical seasonal allergic rhinitis would be hay fever, while a year round would be a response to an indoor allergen such as cat dander. There can be a single source or multiple indoor exposures, such as dust mites, mold and animal danders, which cause symptoms.

For the allergic individual, the allergic response begins with exposure to an allergen and the period of sensitization varies greatly, ranging from a few weeks to decades. Many people do not become sensitized until after years of exposure.

Your body is equipped with a type of cells called mast cells, which are present in the nose and airways (Figure A). As the body becomes sensitized over time to a specific type of allergen (such as cat dander), it produces antibodies (such as IgE), which accumulate and attach to the mast cells (Figure B).

Typically, antibodies are considered as the body's defense mechanism when fighting against infection. However, in an allergic individual, this immune response is reacting to a particle that many people can tolerate without difficulty.

In an allergic individual, the IgE antibodies are produced against specific allergens. When the individual is re-exposed to the allergen, the allergen particle connects with the IgE antibodies causing an allergic reaction (Figure B).

A mast cell releases chemical mediators, such as histamine and leukotrienes, causing the familiar symptoms of sneezing, runny nose, itchy eyes, and/or tightening of the airways (Figure C).

Cat Allergy

An estimated six million Americans are allergic to cats and approximately one third of them have cats in their homes. Allergic reactions to cats can range from inflammation of the nose and eyes to asthma attacks. Although the most effective treatment is removal of the pet, recent scientific studies have shown that steps can be taken in homes with cats to significantly decrease one's exposure to cat allergen.

What Is Cat Allergen?

Cat allergen, the allergy-causing material from cats, is not actually cat hair but instead a protein present in the dander and saliva of cats. The allergens become airborne as microscopic particles which, when inhaled into the nose or lungs, can produce allergic symptoms. Although individual cats may produce more or less allergen, there is no relationship between the pet's hair length and allergen production. There is also no such thing as a non-allergenic breed.

Cat allergen is present to the greatest extent in homes with cats, but has also been found in homes where cats have never been present and in offices and public spaces where animals are not allowed.

Cat allergen is particularly sticky and is carried on clothing. It is almost impossible not to be exposed to some level of cat allergen. Of course, the levels of exposure will be much higher where cats are present, and these levels are more likely to cause allergy symptoms.