Contrary to conventional wisdom, animal hairs are not the real culprits in the overwhelming majority of pet allergies. In the first place, the proteins in hair are not particularly allergenic. In the second place, because hairs are relatively large and heavy materials that tend to settle where they fall, they do not ordinarily remain airborne long enough to trigger significant allergic respiratory problems. Obviously, then, there is little merit to the widely held belief that long-haired breeds are more allergy-provoking than short-haired ones.

If your pet's hairs are not the real problem, then what is? The answer is that animal dander, the flaky, dandrufflike skin cells that your pet sheds by the millions each day, is believed to be the chief allergy troublemaker. Like pollens and mold spores, dander is considered an aeroallergen because it can be easily blown about by the air and is small enough to remain airborne for many hours. As a result, dander may be inhaled deeply into the breathing tubes and lungs where it is capable of producing severe allergic reactions. Individuals with a family or personal history of asthma, hay fever, or eczema appear to be especially prone to pet allergies.

But dander is not the only culprit that has been linked to pet allergies. Pets also shed other kinds of allergens into the air, mostly from their saliva and urine. When these fluids dry out on carpets or furniture surfaces, they then can flake off, become airborne, and eventually permeate the entire house. In general, these substances are sticky and attach to walls, clothing, and even other dust particles. In this way they are spread over large areas, causing problems throughout the home and even in homes that have never had pets.