Pet allergy is an allergic reaction to proteins found in an animal's skin cells, saliva or urine. Signs of pet allergy include those common to hay fever, such as sneezing and runny nose. Some people may also experience signs of asthma, such as wheezing and difficulty breathing.

Most often, pet allergy is triggered by exposure to the dead flakes of skin (dander) a pet sheds. Any animal with fur can be a source of pet allergy, but pet allergies are most commonly associated with cats and dogs.

If you have a pet allergy, the best strategy is to avoid or reduce exposure to the animal as much as possible. Medications or other treatments may be necessary to relieve symptoms and manage asthma.

Pet allergy signs and symptoms caused by inflammation of nasal passages include:

• Sneezing
• Runny nose
• Itchy, red or watery eyes
• Nasal congestion
• Itchy nose, roof of mouth or throat
• Postnasal drip
• Cough
• Facial pressure and pain
• Frequent awakening
• Swollen, blue-colored skin under your eyes
• In a child, frequent upward rubbing of the nose

If your pet allergy contributes to asthma, you may also experience:

• Difficulty breathing
• Chest tightness or pain
• Audible whistling or wheezing sound when exhaling
• Trouble sleeping caused by shortness of breath, coughing or wheezing

Skin symptoms

Some people with pet allergy may also experience skin symptoms, a pattern known as allergic dermatitis. This type of dermatitis is an immune system reaction that causes skin inflammation. Direct contact with an allergy-causing pet may trigger allergic dermatitis, causing signs and symptoms, such as:

• Raised, red patches of skin (hives)
• Eczema
• Itchy skin

When to see a doctor

Some signs and symptoms of pet allergy, such as a runny nose or sneezing, are similar to those of the common cold. Sometimes it's difficult to know whether you have a cold or an allergy. If symptoms persist for more than two weeks, you might have an allergy.

If your signs and symptoms are severe — with nasal passages feeling completely blocked and difficulty sleeping or wheezing — call your doctor. Seek emergency care if wheezing or shortness of breath rapidly worsens or if you are short of breath with minimal activity.

Allergies occur when your immune system reacts to a foreign substance such as pollen, mold or pet dander.

Your immune system produces proteins known as antibodies. These antibodies protect you from unwanted invaders that could make you sick or cause an infection. When you have allergies, your immune system makes antibodies that identify your particular allergen as something harmful, even though it isn't.

When you inhale the allergen or come into contact with it, your immune system responds and produces an inflammatory response in your nasal passages or lungs. Prolonged or regular exposure to the allergen can cause the ongoing (chronic) airway inflammation associated with asthma.

Cats and dogs

Allergens from cats and dogs are found in skin cells the animals shed (dander), as well as in their saliva, urine and sweat and on their fur. Dander is a particular problem because it is very small and can remain airborne for long periods of time with the slightest bit of air circulation. It also collects easily in upholstered furniture and sticks to your clothes.

Pet saliva can stick to carpets, bedding, furniture and clothing. Dried saliva can become airborne.

So-called hypoallergenic cats and dogs may shed less fur than shedding types, but no breed is truly hypoallergenic.

Rodents and rabbits

Rodent pets include mice, gerbils, hamsters and guinea pigs. Allergens from rodents are usually present in hair, dander, saliva and urine. Dust from litter or sawdust in the bottom of cages may contribute to airborne allergens from rodents.

Rabbit allergens are present in dander, hair and saliva.

Other pets

Pet allergy is rarely caused by animals that don't have fur, such as fish and reptiles.

Pet allergies are common. However, you're more likely to develop a pet allergy if allergies or asthma runs in your family.

Being exposed to pets at an early age may help you avoid pet allergies. Some studies have found that children who live with a dog in the first year of life may have better resistance to upper respiratory infections during childhood than kids who don't have a dog at that age.

Sinus infections

Ongoing (chronic) inflammation of tissues in the nasal passages caused by pet allergy can obstruct the hollow cavities connected to your nasal passages (sinuses). These obstructions may make you more likely to develop bacterial infections of the sinuses, such as sinusitis.

Asthma

People with asthma and pet allergy often have difficulty managing asthma symptoms. They may be at risk of asthma attacks that require immediate medical treatment or emergency care.

If you don't have a pet but are considering adopting or buying one, make sure you don't have pet allergies before making the commitment.

Your doctor may suspect a pet allergy based on symptoms, an examination of your nose, and your answers to his or her questions. He or she may use a lighted instrument to look at the condition of the lining of your nose. If you have a pet allergy, the lining of the nasal passage may be swollen or appear pale or bluish.

Allergy skin test

Your doctor may suggest an allergy skin test to determine exactly what you're allergic to. You may be referred to an allergy specialist (allergist) for this test.

In this test, tiny amounts of purified allergen extracts — including extracts with animal proteins — are pricked into your skin's surface. This is usually carried out on the forearm, but it may be done on the upper back.

Your doctor or nurse observes your skin for signs of allergic reactions after 15 minutes. If you're allergic to cats, for example, you'll develop a red, itchy bump where the cat extract was pricked into your skin. The most common side effects of these skin tests are itching and redness. These side effects usually go away within 30 minutes.

Blood test

In some cases, a skin test can't be performed because of the presence of a skin condition or because of interactions with certain medications. As an alternative, your doctor may order a blood test that screens your blood for specific allergy-causing antibodies to various common allergens, including various animals. This test may also indicate how sensitive you are to an allergen.

The first line of treatment for controlling pet allergy is avoiding the allergy-causing animal as much as possible. When you minimize your exposure to pet allergens, you generally should expect to have allergic reactions that are less often or less severe.

It's often difficult or impossible to eliminate completely your exposure to animal allergens. Even if you don't have a pet, you may unexpectedly encounter pet allergens transported on other people's clothes.

In addition to avoiding pet allergens, you may need medications to control symptoms.

Allergy medications

Your doctor may direct you to take one of the following medications to improve nasal allergy symptoms:

• Antihistamines reduce the production of an immune system chemical that is active in an allergic reaction, and they help relieve itching, sneezing and runny nose.

  Prescription antihistamines taken as a nasal spray include azelastine (Astelin, Astepro) and olopatadine (Patanase). Over-the-counter (OTC) antihistamine tablets include fexofenadine (Allegra Allergy), loratadine (Claritin, Alavert) and cetirizine (Zyrtec Allergy); OTC antihistamine syrups are available for children. Prescription antihistamine tablets, such as levocetirizine (Xyzal) and desloratadine (Clarinex), are other options.

• Corticosteroids delivered as a nasal spray can reduce inflammation and control symptoms of hay fever. These drugs include fluticasone propionate (Flonase Allergy Relief), mometasone furoate (Nasonex), triamcinolone (Nasacort Allergy 24HR) and ciclesonide (Omnaris). Nasal corticosteroids provide a low dose of the drug and have a much lower risk of side effects than do oral corticosteroids.

• Decongestants can help shrink swollen tissues in your nasal passages and make it easier to breathe through your nose. Some over-the-counter allergy tablets combine an antihistamine with a decongestant.

  Oral decongestants can increase blood pressure and generally shouldn't be taken if you have high blood pressure, glaucoma or cardiovascular disease. Talk to your doctor about whether you can safely take a decongestant.

  Over-the-counter decongestants taken as a nasal spray may briefly reduce allergy symptoms. If you use a decongestant spray for more than three days in a row, it can contribute to congestion.

• Leukotriene modifiers block the action of certain immune system chemicals. Your doctor may prescribe montelukast (Singulair), a prescription tablet, if corticosteroid nasal sprays or antihistamines are not good options for you.

  Possible side effects of montelukast include upper respiratory infection, headache and fever. Less common side effects include behavior or mood changes, such as anxiousness or depression.

Other treatments

• Immunotherapy. You can "train" your immune system not to be sensitive to an allergen. Immunotherapy is delivered through a series of allergy shots.

  One to 2 weekly shots expose you to very small doses of the allergen, in this case, the animal protein that causes an allergic reaction. The dose is gradually increased, usually during a 4- to 6-month period.

  Maintenance shots are needed every four weeks for 3 to 5 years. Immunotherapy is usually used when other simple treatments aren't satisfactory.

• Nasal irrigation. You can use a neti pot or a specially designed squeeze bottle to flush thickened mucus and irritants from your sinuses with a prepared saltwater (saline) rinse.

  If you're preparing the saline solution yourself, use water that's contaminant-free — distilled, sterile, previously boiled and cooled, or filtered with a filter that has an absolute pore size of 1 micron or smaller. Be sure to rinse the irrigation device after each use with contaminant-free water, and leave open to air-dry.

Avoiding exposure to pets is the best remedy for pet allergy. For many people that doesn't sound like a good option, because family members are often very attached to their pets. Talk to your doctor about whether reducing exposure to your pet, rather than finding a new home for your pet, may be sufficient for managing your pet allergy.

If you find a new home for your pet

If you do find a new home for your pet, your allergy symptoms won't disappear immediately. Even after a thorough cleaning, your house may have significant levels of pet allergens for several weeks or months. The following steps can help lower pet allergen levels in a newly pet-free home:

• Clean. Have someone without pet allergies clean the entire house, including a thorough washing of the ceilings and walls.
• Replace or move upholstered furniture. Replace upholstered furniture if possible, as cleaning won't remove all pet allergens from upholstery. Move upholstered furniture from your bedroom into another area of your home.
• Replace carpets. If possible, replace carpeting, particularly in your bedroom.
• Replace bedding. Replace sheets, blankets and other bedcovers, because it's difficult to wash away pet allergens completely. Replace bed pillows. If you can't replace your mattress and box spring, encase them in allergen-blocking covers.
• Use 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. HEPA air purifiers also may reduce airborne pet allergens.

If you keep your pet

If you keep your pet, you can help minimize the allergens in your home with these tips:

• Bathe your pet frequently. Ask a family member or friend without allergies to bathe 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 allergen levels in those rooms.
• Remove carpeting and dander-attracting furnishings. If possible, replace wall-to-wall carpeting with tile, wood, linoleum or vinyl flooring that won't harbor pet allergens as easily. Consider replacing other allergen-attracting furnishings, such as upholstered furniture, curtains and horizontal blinds.
• 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 pet allergies to do the work.
• Use high-efficiency filters. High-efficiency particulate air (HEPA) air purifiers and vent filters may help reduce airborne pet allergens.
• Keep your pet outside. If your pet can live comfortably outside, you can reduce the amount of allergens in your home. This option isn't appropriate for many pets or in certain climates.

If you're experiencing runny nose, sneezing, wheezing, shortness of breath or other symptoms that may be related to an allergy, you'll most likely start by seeing your family doctor. Because appointments can be brief, and because there's often a lot of ground to cover, it's a good idea to prepare for your appointment.

What you can do

• Write down any symptoms you're experiencing, including any that may seem unrelated to allergy-like symptoms.
• Write down your family's history of allergy and asthma, including specific types of allergies if you know them.
• Make a list of all medications, vitamins or supplements you're taking.
• Ask if you should stop any medications, for example, antihistamines that would alter the results of an allergy skin test.

Preparing a list of questions will help you make the most of your time together. For symptoms that may be related to pet allergy, some basic questions to ask your doctor include:

• What is the most likely cause of my signs and symptoms?
• Are there any other possible causes?
• Will I need any allergy tests?
• Should I see an allergy specialist?
• What is the best treatment?
• I have other health conditions. How can I best manage these conditions together?
• If I have a pet allergy, can I keep my pet?
• What changes can I make at home to reduce my symptoms?
• Is there a generic alternative to the medicine you're prescribing?
• Are there any brochures or other printed material that I can take home with me? What websites do you recommend visiting?

In addition to the questions that you've prepared to ask your doctor, don't hesitate to ask questions during your appointment.

What to expect from your doctor

Your doctor is likely to ask you a number of questions. Being ready to answer them may reserve time to go over any points you want to spend more time on. Your doctor may ask:

• When did you first begin experiencing symptoms?
• Are symptoms worse at certain times of the day?
• Are the symptoms worse in the bedroom or other rooms of the house?
• Do you have pets, and do they go into bedrooms?
• What kind of self-care techniques have you used, and have they helped?
• What, if anything, appears to worsen your symptoms?

Issues if you have asthma

If you have already been diagnosed with asthma and you are having difficulty managing the disease, your doctor may talk to you about the possibility of allergies. Although allergies are a major contributing factor to asthma, the influence of allergy on asthma isn't always obvious.

The impact of a pollen allergy may be noticeable because the allergy is seasonal. For example, you may have more difficulty managing your asthma for a short time during the summer.

Pet allergy, on the other hand, may be due to a pet that you're exposed to throughout the year. Even if you don't have a pet, you may be exposed to pet allergens in other people's homes or that have been transported on people's clothes at work or school. Therefore, you may not recognize allergy as a factor possibly complicating your asthma when, in fact, it may be a primary cause.

What you can do in the meantime

If you suspect that you may have a pet allergy, take steps to reduce your exposure to your pets. Keep pets out of your bedroom and off upholstered furniture, and wash your hands immediately after touching pets.