Does your dog make you sneeze? Does your cat start your eyes watering? If so, you're not alone. Having a pet allergy — whether to dogs or cats, or even to hamsters or birds — is fairly common.

You may be surprised to learn that in most cases it's not your pet's fur or feathers that cause the allergic reaction. Instead, it's the small, invisible flakes of animal skin (dander) that trigger the itchy, watery eyes, sneezing and stuffy nose in people with a pet allergy. Less frequently, pet saliva may cause an allergic reaction in some people.

A pet allergy can range from mild to severe. Symptoms of a pet allergy often occur within minutes after exposure to the pet. The most effective way to alleviate the signs and symptoms of a pet allergy is to find a new home for your pet, although for many people, separating from a loyal companion can be difficult to do.

When you have a pet allergy, you may exhibit the signs and symptoms of hay fever (allergic rhinitis). Signs and symptoms may include:

• Sneezing
• Runny nose
• Itchy, watery eyes
• Nasal congestion
• Itchy nose, roof or mouth or throat
• Postnasal drip

If you have direct contact with the cause of the allergy (allergen), you may experience a rash and itching.

If you have asthma, you may also experience increased signs and symptoms of asthma, such as:

• Lung congestion
• Wheezing
• Shortness of breath
• Cough

Signs and symptoms usually occur within minutes of exposure to pet dander or saliva. If your sensitivity to the allergen is low, however, signs and symptoms may not appear until hours after contact.

The tiny dander particles on your pet are sticky. They'll stick to you, your clothes and the carpets and furnishings in your home. They also can be carried through the air. Pet saliva can stick to carpets, bedding, furniture and clothing.

In most people, pet dander and saliva are harmless. But if you have a sensitized immune system, when these allergens enter your body — whether you inhale them or they enter through the membranes that line your eyes and nose as a result of being licked — they cause an allergic reaction.

During the sensitization process, your immune system mistakenly identifies the allergen as an invader and produces an antibody against it called immunoglobulin E, or IgE.

Then the next time you're exposed to the pet's dander or saliva, your immune system launches an allergic reaction. The preformed IgE antibodies trigger the release of an inflammatory chemical called histamine, which swells the mucous membranes in your nose, sinuses and eyes, causing a runny nose, watery eyes and sneezing.

Pet allergies are common. However, you're more likely to develop sensitivity to pet dander if pet allergies run in your family.

Some research shows that a history of exposure to pets (such as cats) in early childhood actually decreases the risk of developing animal allergy. But it's not known whether deliberate early exposure helps or is harmful.

If you experience the signs and symptoms, such as sneezing, runny nose and watery eyes, and you suspect pet dander or another allergen is to blame, see your doctor for an evaluation. Allergy skin tests — which expose your skin to purified extracts of allergy-causing substances — can help your doctor determine whether you have a pet allergy.

Also, check with your doctor if you have asthma and your symptoms get worse after being exposed to a new pet in the home.

If you experience persistent sneezing, watery eyes and runny nose, your doctor will likely recommend a puncture, prick or scratch (percutaneous) skin test to determine whether your signs and symptoms are caused by an allergy.

In this test, tiny drops of purified allergen extracts — including an extract for pet dander — are pricked or scratched into your skin's surface. This is usually carried out on the forearm, though it may be done on the upper back in children.

Your doctor or nurse will clean the test site with alcohol, and then use a sharp instrument (lancet) to introduce individual extracts into your skin's surface. This causes only little, if any, discomfort.

The drops are left on your skin for 15 minutes before your doctor or nurse observes your skin for signs of allergic reactions. If you're allergic to pet dander, you'll develop a red, itchy bump where the pet dander extract was scratched into your skin.

The most common side effects of these skin tests are itching and redness. These usually subside within a few hours, although they can persist until the next day.

Your doctor may also recommend allergy blood tests, especially if the allergy skin tests can't be completed.

You're more likely to develop asthma — a condition in which the main air passages of your lungs (bronchial tubes) become inflamed and your airways become narrowed — if you're already sensitive to environmental allergens, including pet dander.

If you already have asthma, then pet allergy or exposure to pets can cause an increase in asthma signs and symptoms, including shortness of breath, wheezing and coughing.

If you choose to keep your pet despite doctors' recommendations, doing so may make your reactions more severe and lead to other health problems, such as asthma and eczema, an inflammation of the skin.

The most effective treatment for pet allergy is to avoid exposure to animals. If you own a pet, your best bet is to find it a good home and then vigorously clean your home to remove as much of the allergens as possible.

If your allergy is mild and you'd like to keep your pet, prevention measures may help minimize your exposure to pet dander and the resulting allergic reactions.

Medications
When you can't control your allergic reactions to pet dander with prevention measures, your doctor may recommend or prescribe allergy medications. These may include:

• Nonprescription medications. To counter the signs and symptoms of allergy-induced hay fever, short-acting antihistamines (Benadryl, Claritin, others), decongestants (Sudafed, Chlor-Trimeton, others) or a nasal spray containing cromolyn sodium (NasalCrom) may help.
• Prescription hay fever medications. These include longer acting antihistamines (Zyrtec, Clarinex, others), nasal corticosteroid sprays (Flonase, Nasonex, others) to reduce inflammation, and the leukotriene inhibitor montelukast (Singulair), which blocks the action of leukotrienes — immune system chemicals that cause allergy signs and symptoms, such as excess mucus production.

If your pet allergy is causing asthma symptoms, your doctor may prescribe: inhaled corticosteroids (Flovent, Pulmicort, others); long-acting beta-2 agonists (Serevent, Foradil); combination inhaled corticosteroids plus long-acting bronchodilators — fluticasone and salmeterol (Advair Diskus); and short-acting beta-2 agonists such as albuterol (Proventil, Ventolin), which help open up the airways in your lungs.

Immunotherapy
If your symptoms are especially difficult to control or are causing troublesome nose, eye or asthma symptoms, your doctor may recommend allergy shots (immunotherapy) to desensitize you to pet dander.

In immunotherapy, you'll receive injections of pet dander extract in increasing doses once or twice a week. Once a maintenance dose has been reached, you'll need injections every four weeks.

Avoiding exposure to pets — and their dander — is the best prevention for a pet allergy.

Giving up your cat or dog is the only way to permanently reduce the amount of dander in your home. However, removing your pet from your house won't make your allergies disappear instantly. It can take several weeks to several months for the dander in your house to dwindle to the point that it no longer causes your symptoms.

Once you've found a safe new home for your pet, a thorough cleaning — from scrubbing your walls to replacing your furniture — will remove dander more quickly. It's also a good idea to replace any bedding and carpeting that has animal dander in it. It can take months to fully remove allergens from bedding fabrics, and most vacuums won't clean the lowest levels of carpeting. Vacuuming may actually stir up allergen particles and send them back into the air. Using a high-efficiency particulate air (HEPA) filter may help.

If you keep your pet
If you aren't willing to give up your pet, you can help minimize the allergens in your home with these tips:

• Groom your pet frequently. Ask a family member or friend without allergies to help by bathing your pet on a weekly basis.
• Establish a pet-free zone. Make certain rooms in your house, such as your bedroom, pet-free zones to reduce the levels of allergen in those rooms. Realize, however, that pet dander is easily transmitted through the air and on clothing.
• Remove dander-attracting furnishings. Replace carpets with linoleum or hardwood floors. Exchange your fabric furniture for vinyl or leather. Take down your cloth drapes and put up plastic blinds instead. These new furnishing won't attract and hold pet dander.
• Enlist help. When it comes time to clean your pet's kennel, litter box or cage, ask a family member or friend who doesn't have allergies to do the dirty work.
• Try high-efficiency filters. High-efficiency particulate air (HEPA) filters for your air ducts may trap allergens in the air, and HEPA vacuum bags may reduce the amount of dander rustled up by your cleaning. However, more research needs to be conducted on whether HEPA filters significantly decrease allergy symptoms.
• Keep your pet outside. This is not an appropriate option for all pets or climates. Also, it's important to note that even homes with outdoor pets have higher concentrations of pet dander because dander can be carried inside on clothing.

Realize that the above tactics may not work. You may try all of the tips listed here and still have bothersome allergies. In this case, it may be necessary to place your pet in another home.

Before you get a pet
If you don't have a pet but are considering adopting or buying one, make you sure don't have pet allergies before making the commitment. Spend time at your local Humane Society or with a friend's dog or cat first.