Ask Elizabeth: February 2014

Itching for Answers About the Cause of Cat Allergies

Q. We have two Maine Coons and a Pixie Bob, all longhaired cats. A friend told me that they do not cause allergies in humans, as shorthaired cats do. People will not come to our home because they say they are allergic to cats. But a few people who have come not knowing that we have cats do not seem to have a reaction. I would greatly appreciate some discussion from you.

A. Thanks for contacting me about this common question. I know that you must be itching for an answer. Sorry, I couldn’t help that, anymore than I can resist scratching a flea! Perhaps a few facts about human cat allergies will be instrumental.

An allergic reaction is caused by an overreaction of the body’s immune system to a foreign protein (an allergen) that is either inhaled, eaten, touched or injected. Such a reaction results in the production and/or release of compounds that cause inflammation, which is characterized by redness, swelling, itchiness and pain. Signs of allergies include a runny nose, sneezing, coughing and a scratchy throat. In rare cases, allergies can trigger potentially life-threatening asthma attacks in extremely sensitive individuals.

Cat allergies are very common in the U.S. They are, in fact, the most common pet allergy, with up to 15 percent of people suffering from this condition. Contrary to popular belief, allergic individuals do not react to a cat’s fur purr se. Rather, they react to one or more of a number of proteins secreted in a cat’s saliva and/or their oily skin secretions. The most common culprit is a protein called Fel d1, which is secreted in cat saliva and by cat skin oil (sebaceous) glands. So you see, the length of a cat’s hair is not really a major factor in determining whether people suffering from cat allergies will react. Rather, it is the amount of Fel d 1 produced by a cat.

The amount of Fel d1 that a cat produces may be affected by a number of factors, including gender (male cats produce more) and reproductive status (intact males produce more than neutered cats). As far as we know, hair length is not related to the amount of Fel d 1 allergen that a cat produces, and it is therefore impossible to predict whether a cat will induce an allergic response in sensitive individuals based upon hair length alone.
It is interesting to note, though, that some cat breeds produce less Fel d 1 than other breeds, making them less likely to cause an allergic reaction in those suffering from cat allergies. While these breeds may be more tolerable, there are no known cat breeds that do not produce Fel d 1, making all breeds a potential source of reaction in people with cat allergies.

A number of other factors may affect whether a sensitized individual will react to cats in a specific circumstance. Proximity to cats, the cleanliness of the environment, air purification and how recently a cat has been brushed can affect the likelihood that a cat will cause an allergy sufferer any problems. In terms of things that can be done to minimize the likelihood of an allergic reaction, the easiest is for those with allergies to avoid direct contact with cats. Frequent bathing and brushing of cats minimize the amount of allergens in their environment, and regular washing of bedding and toys does as well, so these precautions can be helpful. Finally, air purification is another means of decreasing the likelihood of allergic reactions.

So while I’m very glad to hear this, it’s hard to know for sure why some people with cat allergies don’t have problems at your house. It might be a combination of the fact that your kitties don’t produce much Fel d 1 and that you are very clean! In any event, I hope this information is helpful. Give my regards to your babies, keep in touch, and let me know how things are going … achoo! Excuse me.

—Best regards, Elizabeth ❖