Cat allergies are a common form of allergy in the United States. According to the American Academy of Allergy, Asthma and Immunology (AAAAI), nearly 10 million pet owners are allergic to their animals.

Cats can cause allergic reactions in people with allergies specific to cats and in people with allergic asthma, a condition in which the airways become blocked or narrowed due to an allergic reaction. Symptoms of cat allergies include sneezing, itchy and watery eyes, coughing and wheezing. In rare circumstances, cat allergies cause the severe and possibly life-threatening allergic reaction known as anaphylaxis.

Allergic reactions may be triggered by proteins in the cat’s dander (dried flakes of shed skin) as well as proteins in dried saliva, blood and urine. These proteins are very light and sticky and can adhere to places where the cat is not present, such as walls and air ducts. Cats groom themselves continually, which produces a regular supply of dried saliva proteins that can then become airborne and be transported throughout a cat’s environment and beyond.

The most effective method to prevent allergy symptoms is avoidance – completely avoiding contact with the allergen to prevent an allergic reaction from occurring. Although medications (e.g., antihistamines, decongestants) and allergy shots (immunotherapy) can be used to relieve or lessen allergy symptoms, cat owners with significant cat allergies must remove the animal from their home. Cats must also be removed from the homes of people with cat induced asthma.

People with cat allergies have allergic reactions after coming into contact with cats. A cat allergy occurs when the body's immune system overreacts to a normally harmless substance associated with the cat. The protein enters the body and starts a cascade of events that triggers the immune system and eventually leads to an allergic reaction.

Contrary to popular perception, it is not the cat’s hair that causes most allergic reactions. Rather, it is protein in flakes of skin (dander) and dried saliva, urine and blood that trigger reactions. While many animals have proteins in their saliva that can trigger allergies, cat allergies are the most common. This is because cats groom themselves continually, which results in a great deal of saliva on the animal and in the animal's environment.

According to the American Academy of Allergy, Asthma and Immunology (AAAAI) nearly 10 million pet owners are allergic to their animals. Cat allergies may not develop quickly, sometimes appearing after more than two years of exposure. Kittens produce less dander than adult cats which is why people with cat allergies, especially children, may be able to tolerate kittens but not adult cats.

Direct contact with a cat is not needed to develop or trigger an allergy. Flakes from dander, saliva and urine proteins are extremely lightweight and easily become attached to larger particles, which can then become airborne or stick to surfaces or objects. These allergen particles remain in an environment for weeks or months after a cat has departed. In addition, cat saliva proteins dry on the cat’s hair and become airborne when the cat is stroked.

Cat allergens are even more likely to be transported through the air than dog dander. Cat dander is lighter and even stickier than dog dander, which makes it more likely that the proteins will stick to other material and be carried farther in the air. Cat allergens can be airborne for extended periods of time, even several months.

A cat does not have to live within a home for its allergens to be present. Owners that keep their cats outside may bring the cat allergens inside with them on their clothing. Studies have indicated that non-cat owners had significantly higher levels of cat dander on their clothing at the end of the working day after coming into contact with cat owners.

In some cases, the amount of cat allergen found on these individuals was quite high. Therefore, people can experience an allergic reaction to a cat without ever sharing an environment with a cat.

Cat allergen also continues to affect the lungs long after exposure. One study found that cat allergen can impair lung function in people with asthma for up to 22 hours after the animal is gone.

Some people have allergies to fleas. As a result, a flea-infested cat may trigger an allergic reaction. In this situation, it is not the cat but the fleas that are the source of the allergy. People with flea allergies develop intense itching and reddening at the bite site.

Cats and dogs are the primary causes of animal allergies. This is likely due to the fact that they are the pets most commonly kept inside of the house. However, other furred or feathered animals (e.g., ferrets, hamsters, guinea pigs, monkeys, horses, rabbits, birds) also cause allergies. People with cat allergies can safely keep pets without fur or feathers, such as fish, snakes and turtles.

Cat allergies are caused by the proteins found in the dander, saliva, blood and urine of cats.

Dander (tiny flakes of dead skin) is continually shed by animals. Proteins that are secreted by oil glands in the cat’s skin are also attached to this dander. Since cats are constantly shedding dander, allergens are deposited around any area in which the animal is present. Dander and dried saliva are also carried by air currents, even into areas the cat has not been (e.g., air ducts, walls). The proteins in dried urine tend to stay indoors because many cats use indoor litter boxes. In contained areas, such as a home, the overall accumulation of dander, urine, blood and saliva proteins is often enough to trigger an allergic reaction in people with cat allergies.

Saliva, urine, blood and dander allergens are present in all cats, even breeds labeled as non-allergenic. There is no such animal as a hypo-allergenic cat. Regardless of breed, size and hair, all cats may cause allergic reactions. Hairless cats have dander and release that dander by grooming themselves as often as haired cats. However, male cats may produce more of the proteins that trigger allergic reactions than females or neutered male cats.

The signs and symptoms of cat allergies are similar to those of other allergic conditions. Symptoms may include:

• Sneezing
• Coughing
• Wheezing
• Shortness of breath  
• Stuffy nose
• Itchy and watery eyes
• Skin rash

The severity of allergic reactions to cats varies between patients. Highly sensitive people may begin experiencing symptoms within 15 to 30 minutes of exposure to cat allergens. People who are less sensitive may not develop symptoms for several days after contact with the allergens. The level of cat allergens in an environment also plays a role in the timing of a patient’s symptoms. Symptoms typically occur sooner when allergen levels are high.   

In rare circumstances, a person with a cat allergy experiences anaphylaxis. This is a severe potentially life-threatening allergic reaction that requires emergency medical attention. Symptoms of anaphylaxis include:

• Shortness of breath
• Tightness in the chest
• Swelling of the lips, face, throat or tongue
• Lowered blood pressure

Physicians trying to determine the cause of an allergic reaction will compile a medical history and a list of symptoms. They will also perform a physical examination.

In addition, an allergy skin test may be performed to help diagnose the patient. This test involves introducing a small amount of an allergen to the patient’s skin to determine if the person is allergic to that allergen. If a rash or small bump develops, the patient is most likely allergic to that substance. Physicians typically test for dander first. If the test is negative, the physician may test for other allergens, such as saliva and urine.

Alternatively, a physician may order a blood allergy test. These tests look for the presence of allergy-specific immunoglobulin E (IgE) in the bloodstream. The most commonly used blood test for allergy conditions is the radioallergosorbent test (RAST).

The main form of treatment and prevention for cat allergies is avoidance – completely avoiding contact with cats to prevent the allergic reaction from occurring. However, many cat owners are unwilling or unable to part with their pet.

Therefore, treatment for cat allergies may also include medications like antihistamines and decongestants, as well as allergy shots (immunotherapy). People who choose to keep their cats can also lower their risk for symptoms by keeping the animal out of their bedroom. They should also avoid petting, kissing or hugging the animal.

However, it should be noted that individuals with significant cat allergies, or cat allergies that lead to asthma, must remove their cats.

In the rare instance when anaphylaxis occurs, the patient will require immediate medical attention. An injection of epinephrine is required to reverse the patient’s symptoms.

Preparing questions in advance can help patients to have more meaningful discussions with their physicians regarding their conditions. Patients may wish to ask their doctor the following questions about cat allergies:

1. Do my symptoms indicate a cat allergy?
   
   
2. What tests will you use to determine if I am allergic to cats?
   
   
3. Is it dangerous for me to have a cat?
   
   
4. Are certain breeds less likely to cause a reaction?
   
   
5. What are my treatment options?
   
   
6. I am not willing to give away my cat. How can I reduce my exposure to cat allergens?
   
   
7. Is my child more likely to have cat allergies because I have the condition?
   
   
8. Is it likely I am allergic to other animals as well as cats?