Allergies are physiological reactions caused when the immune system reacts to a specific foreign substance (allergen). In people who are allergic to animals, their bodies are reacting to animal proteins.

Normally, the human body defends itself against harmful substances such as viruses or bacteria, but, sometimes, the defenses aggressively attack usually innocuous substances such as animal proteins, dust, mold or pollen.

The immune system generates large amounts of the antibodies called immunoglobin E (IgE), to attack and destroy the supposed enemy. Each IgE antibody specifically targets a particular allergen: the substance that triggers the allergic reaction. In this disease-fighting process, inflammatory chemicals, such as histamines, cytokines and leukotrienes, are released or produced and some unpleasant (and, in extreme cases, life-threatening) symptoms may be experienced by an allergy-prone person.

Approximately 15 percent of the population is allergic to animals.

Animal fur does not cause animal allergies. Rather, allergy-triggering proteins found in animal dander (dead skin flakes), saliva and urine cause allergic reactions to animals. These proteins, called allergens, are either secreted by an animal's oil glands in its skin and shed as dander or are found in an animal's saliva and urine. When these proteins are shed or dry in animal fur, or become airborne, they can attach to carpeting, furniture and other objects and trigger allergies in people.

Household pets, such as dogs and cats, are the most common sources of animal allergens. But other furry or feathered animals, such as birds and rodents (hamsters, guinea pigs, gerbils, mice etc.), or livestock can cause allergy symptoms. "Non-allergenic" breeds of dogs and cats do not exist and even hairless breeds may cause allergies. Products made with feathers or down, like certain pillows and comforters, may also trigger allergy symptoms.

Medical treatments for allergies include immunotherapy (allergy shots), steroidal and antihistamine nose sprays and antihistamine pills.

Also, good housecleaning, such as frequent vacuuming, and using special air filters, pillows and coverings, can help create allergen-free or allergen-reduced environments. Sending pets outdoors more often, bathing and grooming them, and limiting the number of rooms they are permitted in can also reduce allergy symptoms.

First, be sure that it really is your animal who is provoking your allergic reaction. If you’re allergic to an animal, you are probably allergic to other things as well. By decreasing other irritants, you’ll reduce your overall symptoms. Avoid tobacco smoke, automobile exhaust, and other irritants that can inflame your airways. Here are some other suggestions for decreasing symptoms from allergies to animals:

• Buy inexpensive vinyl encasing for mattresses and box springs, and minimize upholstered furniture. Wash walls, ceilings, blankets, curtains, and throw pillows regularly. The main reservoirs of cat allergens are carpets, drapes, upholstered furniture, mattresses, walls, and ceilings, which catch dust and dander.

• Replace carpets with tile, wood, linoleum, or rugs that can be washed, especially in rooms where you spend a lot of time, such as the bedroom. If you must have carpets, spray them with a product that contains nontoxic tannic acid, which helps combat the effects of cat allergens.

• Use a high-efficiency particulate air (HEPA)-type vacuum—it will capture the small particles of allergens that conventional paper-filter vacuums cannot. Consider getting a HEPA filter room air cleaner, which removes almost 100 percent of allergenic particles. Free-standing cleaners are better than the small, table-top filters. Remember to replace the filters often.

• Provide your animal companions with their own comfortable beds and blankets.

• Always wash your hands after petting your animal companions.

• If possible, have others groom and bathe the animal and clean the litter box. Grooming should be done in a well-ventilated area.

• Beware of dusty or deodorized cat litter, which can be as allergenic as the cat.

• Keep ducts, furnaces, and air conditioner filters clean.

• Ventilate your house. Circulate air in the house by opening windows every day.

• Feed your animal a high-quality diet that includes omega-3 fatty acids; healthy animals produce less dander.

• Be thorough in cleaning—search out dust, mold, and animal hair.

• Minimize or eliminate your consumption of common allergenic foods.