Cat and Dog Allergy

Cats and dogs have kept humans company for thousands of years.  For just as long, they have also been the source of allergies and asthma.

Contrary to popular belief, people are not allergic to an animal’s hair, but rather, to a protein found in the saliva, dander (dead skin flakes) or urine of an animal with fur. These proteins are carried in the air on very small, invisible particles, which can land on the lining of the eyes or nose, or be inhaled directly into the lungs. Usually, symptoms will occur quickly, sometimes within minutes after exposure to the animal. For some people, symptoms may build and become most severe eight to 12 hours after they have had contact with the animal.

A cat or dog produces a certain amount of allergen per week, and this amount can vary from animal to animal. All breeds are capable of triggering symptoms – there are no “hypoallergenic” breeds of cats or dogs*. People with severe allergies can even experience reactions in public places if dander has been transported on pet owners’ clothing.

The most effective way to combat symptoms of animal allergy is to remove the pet from the home and avoid any contact. Keeping an animal outdoors is only a partial solution, since homes with pets in the yard still have higher concentrations of animal allergens. Before you get a pet, spend time with someone else’s dog or cat, the breeder or at an animal shelter to determine if you’re allergic. If you already have an animal to which you or a family member is allergic, try to place it with a caring, non-allergic friend or relative. Although this separation can be difficult, it is best for the health of you or your allergic family member. You may also consider getting a pet such as a turtle, hermit crab, fish, snake, or other animals without fur or feathers.

If you cannot avoid exposure to the animal that causes your allergy symptoms, try to minimize contact. Most importantly, keep the pet out of the bedroom and other rooms where people with allergies spend a great deal of time. Some studies have demonstrated that bathing dogs or cats on a weekly basis may reduce the amount of allergens that are shed in the home. While dander and saliva are the source of cat and dog allergens, urine is the source of allergens from rabbits, hamsters and guinea pigs; ask a non-allergic family member to clean the animal’s cage.

Vacuuming is not effective in decreasing animal allergens, because it does not clean the lower levels of the rug. In fact, it can stir up small allergen particles, which can also move right through the vacuum. Using a HEPA vacuum filter or double bags may help. As with dust mites, the best solution is to have a hardwood floor, tile or linoleum. Although there is no conclusive evidence, some studies have found that using a HEPA air cleaner may reduce animal allergen exposure.

Replace bedding and carpeting that has animal dander in it. It typically takes 6 months for dander levels to fall after removal of the animal to levels that will no longer exacerbate allergy and asthma symptoms.

Frequently Asked Questions

Is there such a thing as a hypoallergenic dog or cat?

  • No*. The major allergen in dogs and cats is a protein found in their serum which they excrete in sweat and shed  from their skin.  Since all dogs and cats have that protein, no dog or cat is completely allergy-free*.

What about dog breeds?

  • A recent study, published this year, that tracked allergies among people exposed to various dog breeds showed that sensitization to dogs can vary from dog-to-dog even within the same breed.   In other words, it was a dog-by-dog issue more than a breed-by-breed issue.

Does the dog’s size or hair length matter?

  • The size of dog could matter in terms of the overall amount of allergen, with smaller dogs contributing less allergen.  Hair length could play a role in how the allergen travels through the house.  Shorter dog hairs may not stick as much as long hair to furniture, clothes, and other surfaces.

What can a family do once they’ve brought a dog or cat home?

  • Keep the dog or cat out of the allergic patient’s bedroom, since the child spends a lot of time there.
  • Wash your hands after petting the dog or cat.
  • Keep the house clean.
  • Consider using an air purifier.
  • Make sure the cat/dog’s coat is healthy and well maintained.  Flaky skin can increase the amount of allergens produced.

Could a dog or cat allergy fade?

  • Allergies to dogs and cats may change over time.  For instance, some patients who grew up with a dog develop symptoms of dog allergies after being away from home for a long time, such as college students returning home for the holidays.  They visit their parents for Thanksgiving … and they have symptoms where they never had symptoms before.
  • Cat allergy can be especially dangerous for asthmatics.  The cat protein is the perfect size to remain airborne and enter deep into the lungs.  This makes cats capable of triggering asthmatic reactions in allergic individuals.

*Update: The hypoallergenic dog and cat

One company has genetically engineered cats and dogs that are missing the allergic protein.  They have three cats to choose from:

  • THE ALLERCA GD – $7,950
  • THE CHAKAN GD – $19,900
  • THE ASHERA GD – $37,000

And one dog:

  • The JABARI GD – $15,000

More information at:

This is a handout from the Asthma and Allergy Affiliates reviewing current knowledge of cat and dog allergy including a review of common beliefs such as hypoallergenic dogs or breeds.  These handouts are intended for our patients and are not a substitute for discussing your (or your child’s) unique situation with one of our physicians.