Pet Allergy

More than 70 percent of U.S. households have a dog or cat. Pets provide companionship, security and a sense of comfort. Children often learn responsibility and lessons about life and death from pets.

However, people with allergies should be cautious in deciding what type of pet they can safely bring into their home. Pet exposure may cause sneezing and wheezing. An estimated 10 percent of the population may be allergic to animals. A higher rate of 20 percent to 30 percent of individuals with asthma have pet allergies.

Pets can cause problems to allergic patients in several ways. Their dander, or skin flakes, as well as their saliva and urine, can cause an allergic reaction. The animal hair is not considered to be a very significant allergen. However, the hair or fur can collect pollen, dust, mold and other allergens.

What Are the Most Common Pets?

The most common household pets are dogs, cats, birds, hamsters, rabbits, mice, gerbils, rats and guinea pigs. Larger animals such as horses, goats, cows, chickens, ducks and geese, even though kept outdoors, can also cause problems as pets.

The number of pets in the United States is estimated at more than 100 million. This large number also increases the likelihood of accidental exposure to animals by the allergic patient when visiting homes, farms, etc.

Both feathers and the droppings from birds, another common pet, can increase the allergen exposure. The allergic patient should not use feather pillows or down comforters. If a feather pillow is used, it should be encased in plastic. An encasing with a zipper is recommended, so none of the feathers can escape.

Bird droppings can be a source of bacteria, dust, fungi and mold. This also applies to the droppings of other caged pets, such as gerbils, hamsters and mice.

What Do Allergists Recommend?

The best types of pets for an allergic patient are pets that don't have hair or fur, shed dander, or produce excrement that creates allergic problems. Tropical fish are ideal, but very large aquariums could add to the humidity in a room, which could result in an increase of molds and house dust mites.

A frequent misconception is that short-haired animals cause fewer problems. It is the dander (skin scales) that causes the most significant allergic reactions - not the length or amount of hair on the pet. As stated previously, allergens are also found in the pet's saliva and urine. In addition, dogs have been reported to cause acute symptoms of allergic conjunctivitis, or inflammation of the eye, and hay fever after running through fields and then coming back into contact with their owners.

Those pets that are known to cause significant allergic reactions should be removed from the home of the allergic patient to avoid possible progression of symptoms. A "trial" removal of a pet for a few days or even weeks may be of little value since an average of 20 weeks is required for allergen levels to reach levels found in homes without pets.

Can Pet Allergies Be Managed?

If the family is unwilling to remove the pet, it should at least be kept out of the patient's bedroom and, if possible, outdoors. Allergic individuals should not pet, hug or kiss their pets because of the allergens on the animal's fur or saliva.

Indoor pets should be restricted to as few rooms in the home as possible. Isolating the pet to one room, however, will not limit the allergens to that room. Air currents from forced-air heating and air-conditioning will spread the allergens throughout the house. Homes with forced-air heating and/or air conditioning may be fitted with a central air cleaner. This may remove significant amounts of pet allergens from the home. The air cleaner should be used at least four hours per day.

The use of heating and air-conditioning filters and HEPA (High Efficiency Particulate Arresting) filters as well as vacuuming carpets, cleaning walls and washing the pet with water are all ways of reducing exposure to the pet allergen. Vacuum cleaners with HEPA filters are now available. However, in a patient with severe symptoms resulting from animal dander exposure, a HEPA filter is not an effective solution.

Litter boxes should be placed in an area unconnected to the air supply for the rest of the home, and should be avoided by the allergic patient.

Some allergic patients may have severe reactions, such as wheezing and shortness of breath, after exposure to certain pets. Also, a chronic, slowly progressive feeling of shortness of breath, loss of energy and feeling of fatigue can result from long-term exposure to birds and their droppings. This type of disease is known as hypersensitivity pneumonitis and can result in severe disability. In the event of these severe cases, removal of the offending animal is mandatory.

How Are Pet Allergies Diagnosed?

The avid pet owner may claim that exposure to his or her pet does not cause their allergy symptoms. This, however, should be viewed skeptically, since pet ownership is an emotionally charged subject. Also, many allergic pet owners are rarely away from their pets, so an accurate reporting of pet-related symptoms may not be possible.

Skin tests or special allergy blood tests are helpful for diagnosing allergy to animals, but are not always accurate. To gain confirmation about a pet's significance as an allergen, the pet should be removed from the home for several weeks and a thorough cleaning done to remove the hair and dander. It should be understood that it can take weeks of meticulous cleaning to remove all the animal hair and dander before a change in the allergic patient is noted.

Are Allergy Shots Effective for Pet Allergies?

Allergy shots (immunotherapy) may be indicated for cat or dog allergies, particularly when the animal cannot be avoided - as might be the case when the patient is a small animal veterinarian. They are typically given for at least three years. They decrease symptoms of asthma and allergy. Usually after about six months of weekly injections allergy symptoms improve and less medication is required

Allergy shots are most effective and safe when administered under the supervision of an allergist-immunologist. The response is highly individual and depends on environmental avoidance as well as the initial sensitivity of the individual

What Can I Do When Visiting People With Pets if I Am Allergic?

The approach to visiting households with pets for an allergic individual is to take appropriate precautions including administration of medications prior to visitation. Your allergist-immunologist can provide information on medications for your animal allergy, such as antihistamines, nasal sprays, decongestants or appropriate asthma medications.

For patients who have severe symptoms on animal dander exposure, the pet should removed from the house at least day before the visit, and the host household should be cleansed of animal allergen to the extent practical.

Updated May 2000