Are you allergic to pets? This is a really common problem, affecting one in 5 Americans, and it is steadily increasing in prevalence. If you're an animal owner, you definitely have friends and acquaintances who couldn't comfortably enter your home. Some of us are even allergic to our own pets! It is virtually impossible to insulate oneself completely from pet allergens because of their physical properties. They are extremely small (even when compared to other microscopic particles), making them difficult to filter or trap. They float very easily, staying aloft for lengthy periods of time (hours to days). Airborne molecules have an excellent opportunity for unrestricted access to an allergic person through the delicate tissues of his or her respiratory system. A sticky outer surface allows them to be carried great distances from the source by adherence to clothing, personal articles, and even human hair. They're found in high concentrations in many public places, even inside the offices of allergy doctors and the homes of people who don't own pets. Once a pet has lived in a particular place, environmental contamination persists for months, regardless of intense cleaning.
Cats are second only to dust mites in the list of most irksome indoor allergies. Cats affect about twice as many people as dogs; however, dog allergies are less likely to be accurately diagnosed. Dogs' bodies produce a hodge-podge of allergenic particles, while a reaction to cats is consistently initiated by a single, specific molecule (about 95% of the time). This makes the cat allergy test extremely reliable and has paved the way for greater scientific advancement in the treatment of cat allergies.
Allergic reactions in humans are not really caused by fur, or even dander, but by the much smaller particles adhered to these items. In cats, the offending molecule is known as Fel d1 (Felis domesticus, antigen #1). It originates in their salivary and skin glands. That's the reason hairless cats still cause allergic reactions (they do still have skin and tongues, after all) and why short-haired cats aren't less problematic. The allergen is distributed efficiently throughout the coat during self grooming, making fur a prominent, albeit innocent, vehicle for this troublesome particle.
The amount of Fel d1 produced by a given cat can not be accurately forecast based on breed or appearance, but male cats tend to produce more and old cats tend to produce less. Although there is no allergy-free cat, it is partially controlled by heredity, and a few breeds do tend to be a little more compatible with the human immune system. Because there is a highly specific test to quantify how much Fel d1 is produced by an individual, it would be theoretically possible to breed a line of cats that produce less of it. A well-publicized attempt was made in 2006; however, the company ended up curtailing their efforts about 4 years later amidst a flurry of negative publicity and customer complaints. In our next installment, how you might still be able to own a cat even if your immune system has explicitly vetoed the idea.
Dr. M.S. Regan
