Pet Allergies (Cat and Dog Allergy) Causes, Symptoms, Tests, Treatment

With almost 2 in 3 American households having one or more pets, allergies to pets are a relatively common problem. Cat allergies are more likely to affect pet owners than dog allergies. There is no cure for pet allergies and treatment largely focuses on easing symptoms and minimizing the reaction to the allergy triggers. For severe allergy sufferers, the only option may be to remove the pet from the household altogether.

What is a pet allergy?

A pet allergy is an immune reaction to pet dander, skin cells, urine and/or saliva that causes inflammation of the airways and/or skin. Most of the time this is referred to as a cat allergy or a dog allergy but the reaction can occur with any animal. However, it is pets like cats and dogs that have the greatest exposure to humans as they live in or near the household and exposure is on a daily basis.

There are many misconceptions that exist with regards to pet allergies. Firstly it is not only a reaction to the pet’s hair or fur (dander) that can trigger the allergic reaction. Even saliva and urine can serve as triggers. Secondly the species of dog or cat and the amount of hair/fur it has will not determine whether it is more or less likely to serve as a trigger. In other words there are no “allergy free” or hypoallergenic species of pets.

How do pet allergies occur?

Allergies are an abnormal immune response to otherwise harmless substances. Normally the immune system is supposed to protect the body when there is a threat. In pet allergies, this immune defense response is abnormally triggered when the body is exposed to proteins from pets like cats and dogs. These substances are essentially harmless. In addition there may also be dust and pollen on a pet which can also serve as an allergy trigger.

These proteins that can trigger an allergic reaction are referred to as allergens. Upon first exposure, the body produces its own proteins in response to these allergens. These proteins produced by the body are known as antibodies. Upon subsequent exposure to the allergen, the antibody then binds to it and triggers and immune response. As a result there is inflammation.

Read more on house dust allergies.

The exact reason why some people will develop a pet allergy and others do not is unclear. People with a family history of pet allergies or allergic conditions are at a greater risk of pet allergies. In addition, overexposure to pet proteins (dander, saliva and urine) may also be a contributing factor to developing an allergy but more so in a hypersensitive or predisposed person.

Signs and Symptoms

The signs and symptoms of pet allergies mainly involves the eyes, nose and airways and sometimes the skin. The pet allergen (dander, saliva or urine) triggers a reaction at the part of the body where it makes contact. The amount of allergen can determine the severity of the allergic reaction as well as the individual hypersensitivity. Therefore some pet allergies may be mild, moderate to severe in intensity.

Allergies are more likely to trigger symptoms when it makes contact with mucous membranes, like the lining of the eyes, nose and airways, in people who are sensitive. The allergens can even reach the lower airways. Skin symptoms are less common than eye and airway symptoms but can occur in some hypersensitive individuals. These skin symptoms are also more likely to arise with scratches as the break in the skin allows the allergen to make contact with living tissue.

Eye and Airway Symptoms

Most of the time the eyes and upper airways are affected in pet allergies.

  • Itching of the eyes
  • Red and watery eyes
  • Puffiness under the eyes
  • Sneezing
  • Runny nose
  • Nasal congestion
  • Postnasal drip
  • Cough

Read more on allergic rhinitis.

Sometimes the lower airways can also be affected and pet allergies may trigger or worsen asthma.

  • Wheezing
  • Difficulty breathing
  • Tight chest
  • Chest pain
  • Coughing

Skin Symptoms

  • Itchy skin
  • Red raised patches
  • Dry rough skin

Tests for Diagnosis

A case history may provide the first indication of a pet allergy. The presence or emergence of the symptoms mentioned above, particularly when making contact with pets or among people who have pets in the household, should prompt the need for further diagnostic investigations. There are two types of tests that can be done to confirm a pet allergy – a skin test and/or a blood test.

Skin Test

A skin prick test is usually preferred as the method to diagnose pet allergies. It is less invasive and often more cost effective than a blood test. In a skin allergen test, a small amount of the allergen is introduced into the skin. If there is a reaction after 15 to 30 minutes then it confirms a pet allergy.

Blood Test

A sample of blood is collected and sent to a laboratory for testing. Allergen proteins are introduced into the sample and if there is a reaction then it confirms the presence of an allergy. Blood tests can also reveal the levels of antibodies which can indicate the severity of the allergy.

Treatment of Pet Allergies

Once a pet allergy is confirmed, treatment is then prescribed. Ideally pet exposure should be avoided but this is not always possible. The treatment is largely aimed at easing or reducing the severity of the allergy symptoms. Some treatment options may also reduce the immune response to the allergens. However, this is not a cure for a pet allergy.

  • Antihistamines block the immune chemical known as histamine thereby providing symptomatic relief.
  • Corticosteroids suppress the immune activity and reduces inflammation.
  • Nasal decongestants also reduce nasal symptoms and eases mucus production.
  • Leukotriene modifiers blocks the immune chemicals known as leukotrienes which cause inflammation.
  • Immunotherapy is a form of desensitization therapy where small amounts of the allergen are introduced into the body to allow the immune system to become less reactive to it.

How to prevent pet allergies?

In order to prevent pet allergies it is important to minimize contact with pets or avoid cats and dogs altogether. Pet allergens remain in the home, in the air and on surfaces, for hours or even days and weeks. People with moderate to severe allergies who are not finding complete relief with medication should consider removing the pet from the home altogether.

However, not every person with a pet allergy will consider removing the pet from the home environment. Therefore contact needs to be minimized by keeping the pet outdoors. The pet should not be allowed inside the home even for short periods. Allergens from pets can remain within the home for as long as 6 months. Regular vacuuming and cleaning can help to some degree by physically removing the allergen from surfaces within the home.


  1. American Academy of Allergy Asthma and Immunology.
  2. Asthma and Allergy Foundation of America.

Please note that any information or feedback on this website is not intended to replace a consultation with a health care professional and will not constitute a medical diagnosis. By using this website and the comment service you agree to abide by the comment terms and conditions as outlined on this page