Allergies to Cats or Dogs

FACTSHEET

What am I allergic to?

One common misconception is the belief that a person is allergic to an animal’s fur. However, the allergic reaction is usually triggered by the dander of a cat or dog. Dander consists of dead skin cells that flake off when the outer layer of skin renews itself, a normal, ongoing process. This turnover is faster in animals who are prone to various skin problems, such as dry skin and oily seborrhea. A cat can sometimes trigger allergic reactions when a dog does not because cat dander is smaller and lighter, so it remains suspended in the air longer than dog dander.

Saliva and urine on the fur of dogs and cats are also potential sources of allergens. When the fur dries, microscopic particles flake off and become airborne. A compound called Fel D1 present in the saliva of cats, and also secreted from their skin glands, can trigger allergic reactions.

What are the symptoms?

About 15% of the population is allergic to cats or dogs and suffers from itchy eyes, runny noses, asthmatic symptoms, itchy skin, or a rash. The severity of the allergy can depend on the amount of allergens you are exposed to. It might depend on the size of the cat or dog, because if the animal is larger, he will most likely shed more dander.

Are there any non-allergenic dogs or cats?

All cats and dogs produce allergenic dander, and any animal with fur or feathers can trigger allergic reactions. Dogs who are shampooed and groomed regularly emit less dander into the air. Female cats have less Fel D1 than males. Cats and dogs who shed profusely are more likely to cause allergic reactions, because there will be an excessive amount of hair covered with saliva and dander in the house. However, as long as your house is vacuumed frequently and cleaned with a mop or sponge, an animal who sheds a lot should not be more of a problem than any other cat or dog.

How can I reduce my allergic symptoms?

There are a many things you can do to reduce allergens and your allergic symptoms.

Care of the animal: Keep your dog’s or cat’s skin healthy by feeding high quality food and a fatty acid supplement. Some studies claim bathing your cat or dog every few weeks will help reduce the amount of allergens released into the air.

Housecleaning: Control the amount of dust and dander in the house by removing carpets, reducing the amount of upholstered furniture, and washing materials that can readily trap animal dander. Installing a high efficiency air (HEPA) filter in your home may also help. Vacuum and mop the floors regularly. Certain solutions, such as 3% tannic acid, will destroy animal allergens in carpets without damaging the carpet.

Taking medication: Various forms of medication are now available that can minimize allergy symptoms. Allergy injections work by gradually desensitizing a person’s immune system to cat or dog allergens (immunotherapy). After a few months of allergy shots once a week, people can usually control their symptoms with one injection a month. Eventually, in some cases, symptoms can be eliminated altogether. Many new medications for controlling allergic symptoms are on the market. Steroid nasal sprays reduce allergic irritation in the sinus area and help reduce inflammation that leads to coughing, wheezing, and chest tightness. For asthma, there are multiple medications, sprays, and inhalers available. Antihistamines will help control a runny nose and itchy eyes. With the right medication, good housecleaning methods, and a healthy cat or dog, it is entirely possible for an allergic person to live happily with an animal companion.

Is it possible to prevent allergies?

Recent studies show there are actually ways to prevent certain allergies from developing. A 2002 study in the Journal of American Medical Association concluded that exposure to two or more dogs or cats in early childhood may reduce subsequent risk of developing allergies.1 The New England Journal of Medicine found that children who grow up in extremely clean homes are far more likely to develop asthma and allergies than those who grow up on farms and in less immaculate homes.2 A study in Lancet showed that children in rural Austria who are exposed to horses and stables before they are one year old have a much lower incidence of asthma and hay fever.3

Scientists theorize that a young immune system without any germs will start attacking things that aren’t germs, such as animal dander. Even when studies factored in family history, smoking, and other variables, they confirm that early exposure to cats, dogs, and other sources of allergens help protect children from later developing asthma and allergies.

Footnotes

¹ E.L. Peterson, C.C. Johnson, & D.R. Ownby, "Exposure to dogs and cats in the first year of life and risk of allergic sensitation at 6 to 7 years of age," JAMA, Aug 2002; 288: 963-972.

² S. Weiss "Eat dirt – the hygiene hypothesis and allergic disease," NEJM, Sep 2002; 347: 930-931.

³ C. Braun-Fahrlander et al, Children's Hospital, Salzburg, Austria, "Exposure to farming in early life and development of asthma and allergy: a cross-sectional survey," Lancet, 2001. 358 (9288): 1129-1133.