Allergens From Dogs, Cats and Other Animals Kept Indoors

What animal allergens are
Where animal allergens are found
Health problems caused by animal allergens
Decreasing exposure to animal allergens 

What Animal Allergens Are 

Animal allergens such as dead skin (dander) and cat saliva are biological contaminants that come from animals. They can travel through the air and are too small to be visible to the unaided human eye. Animal allergens, like other biological contaminants, contribute to poor indoor air quality and may be a major cause of days lost from work and school since they can make you sneeze, trigger allergic reactions, cause rashes, watery eyes, coughing, dizziness, lethargy, breathing difficulties, and digestive problems. Exposure to dust mites, animal dander, cat saliva and mold cause about 200,000 emergency-room visits a year for asthma patients.¹

Household pets are the most common source of allergic reactions to animals. Almost all pets can cause allergies, but especially cats. Small animals like birds, hamsters and guinea pigs can also cause allergies.

Where Animal Allergens Are Found

Many people think that pet allergies are triggered by the fur of household pets. Actually, many of the allergens are proteins secreted by oil glands in the animals' skin and shed as dander or dead skin. Allergenic proteins are also found in saliva and urine. Here are the problems that may be seen with these animals:

• Cats: Domestic cats are an important source of allergens in the home, particularly in northern Europe where the climate is not as favorable to dust mites.² Cat allergens are found in saliva, skin and the dander of cats. Cats may be more likely than dogs to cause allergic reactions through saliva because they lick themselves more and the saliva sticks to the fur. Male cats shed more than female cats so this may release more allergen. When the saliva dries, these proteins, in addition to the proteins in dander, can become airborne and be inhaled. Cats may also be held more and spend more time in the house close to humans, which increases their risk of inhaling these allergens. Cat allergens can remain airborne for extended periods. This could explain why individuals allergic to cats experience allergic symptoms immediately in the presence of a cat.³ In addition to these allergens, cats can also excrete fungi (Toxoplasma gondii) that can be dangerous to one's health.⁴

• Dogs: Dog allergens are mostly found in saliva and dander.
  
  Cats and dogs are the most important sources of indoor allergens in northern Scandinavia and the U.S. mountain states. It has also been demonstrated that heavy flea infestation from these pets can increase the allergens found in house dust.³

• Birds: Pet allergens may be found in the feathers of birds. Birds can also excrete fungi such as Cryptococcus neoformans or Histoplasma capsulatum.⁴

• Guinea pigs, gerbils, mice, and rats: Some rodents, such as guinea pigs and gerbils, have become increasingly popular as household pets. They, too, can cause allergic reactions in some people, as can mice and rats. Urine is the major source of allergens from these animals. This urine is a strong allergen. When it dries, it can become airborne.

Allergies to animals can take two years or more to develop and may not subside until six months or more after ending contact with the animal. Carpet, furniture and other textured materials are reservoirs for pet allergens. In addition, these allergens can stay in household air for months after the animal has been removed. This is because the allergen remains in the house dust. Therefore, it is wise for people with an animal allergy to check with the landlord or previous owner to find out if furry pets had lived previously on the premises.

In some instances, cat and dog allergen levels have even been detected in schools and day care centers where there are no pets. The allergen is carried in on the clothes of children who live in homes with pets.³ 

Health Problems Caused by Animal Allergens 

Cat allergen is found in saliva and skin and is extremely small so it can remain airborne for many hours. Because of the small particle size, cat allergen easily enters the lung and can induce hypersensitivity disease such as asthma. Exposure to other animal allergens is not as important as cat allergens.²

Health problems caused by animal allergens include:

• Asthma attacks

• Running nose

• Sneezing

• Eye irritation

• Cough

• Rash

Decreasing Exposure to Animal Allergens

• If somebody has severe, uncontrollable allergies or asthma around a pet, the first thing to consider is finding a new home for that pet. Sometimes you hear that certain cats or dogs are "non-allergenic." There really is no such thing as a "non-allergenic" cat or dog, especially if the pet leaves dander and saliva in the home. Goldfish and other tropical fish may be a good substitute. If you do get rid of the pet, make sure to do a thorough cleaning including floors, walls, and especially carpets and upholstered furniture since pet allergens can remain in the home for months after the pet is removed. If the pet removed was a cat, a 3% tannic acid solution has been shown to be effective in reducing cat allergen concentrations.³

• If getting rid of the family pet is not an option, consider doing the following:

  • Keep pets in only one area of the home

  • Keep pets out of the bedroom and other sleeping areas at all times, and keep the door closed

  • Keep pets away from fabric-covered furniture, carpets, and stuffed toys

  • Weekly pet baths may help cut down the amount of pet saliva and dander in the home.

  • Keep pets outside

  • Make sure people with asthma stay away from the pet

• Keep the house clean. Animal dander and other allergy-causing agents can be reduced, although not eliminated, through regular cleaning.

• Keep carpets and upholstered furniture vacuumed with high-efficiency collection bags.

• Conduct periodic carpet cleaning with an efficient system proven to remove >99% of allergens

Pet owners are sometimes advised to use air cleaners. Although properly used and maintained air cleaners may reduce animal triggers in small areas, they should only be considered as an addition to other control methods, and the specifications of air cleaners should be carefully investigated. In addition, some air-cleaning devices produce ozone, which may be harmful to asthmatics.

1. Statistics. EHS Services, Inc. Environmental, Health, Safety, and Quality Management Services for Business and Industry, and Federal, State, and Local Government, 1999. Date accessed: February 2001. [www.ehsservices.com/IAQ_stats.htm]

2. Jones AP. Asthma and domestic air quality. Soc. Sci. Med. 1998;47(6):755-764.

3. Fernández-Caldas E, Trudeau WL. Environmental control of indoor biologic agents. J Allergy Clin Immunol. 1994;94(issue 2, part 2):404-412.

4. Seltzer JM. Biologic contaminants. Occupational Medicine: State of the Art Reviews. 1995;10(1):1-25.