Animal Allergies – Causes, Signs and Symptoms

Animal Allergies

Also called: Pet Allergies


An estimated 70 percent of people in the United States live with animals in their homes, according to the American College of Allergy, Asthma and Immunology (ACAAI). For many people, this contact results in nothing out of the ordinary. However, the ACAAI estimates 10 percent of people experience an allergic reaction as the result of an animal allergy. This figure is just an estimate – the actual number of animal-sensitive people may be 20 percent or even higher, according to other sources.

Animal allergies can result in a number of physical reactions, including runny nose, watery eyes, hives or skin rash, and difficulty breathing. There is also a strong link between animal allergies and asthma, as well as other allergies, such as pollen or dust.

Because people are most likely to have dogs and cats in their homes as pets, dog and cat allergies are the most common animal allergies treated and discussed. However, people may be allergic to all types of animals, including other types of pets (e.g., rabbits, hamsters, guinea pigs, rodents, ferrets, birds) and non-household animals (e.g., horses, cows, pigs, moles). In addition, people may react to urine and droppings from animals, including birds, rodents and insects, as well as insect bites and stings.

Animal allergies may also be triggered by products made from animals. This list includes feather pillows and some upholstery (though allergies associated with these are far more likely to be triggered by dust mites).

Animal allergies can appear at any stage in life. A person’s risk of developing an allergy (of any type, including animals) rises if a parent has an allergy (of any type). Treating animal allergies usually begins with avoidance, if possible, but it may include management strategies that can reduce the level of allergens within a person’s home or immunotherapy.

About animal allergies

People with animal allergies have allergic reactions after coming into contact with one or more animals to which they are sensitive. Contrary to popular perception, it is not the animal’s fur that causes most allergic reactions. Rather, it is flakes of skin (dander) and dried urine, saliva or blood proteins that most often trigger an allergic reaction. Reactions are also possible with non-fur animals such as birds and insects.

An animal allergy occurs when the body’s immune system overreacts to a normally harmless substance associated with the animal, usually some type of protein from its dander, saliva or urine. These miniscule proteins are carried through the air, where they can land on the lining of the nose or eyes. They can also be inhaled directly into the lungs. Once the protein enters the body, it starts a cascade of events that triggers the immune system and eventually leads to an allergic reaction.

How this reaction manifests itself often depends on the individual. An allergic reaction can affect the skin, gastrointestinal tract, respiratory system or even the heart and blood vessels. Physical symptoms include sneezing, watery eyes and runny nose. They can also include sore throat, coughing, blotchy skin and other symptoms that may be confused with other causes, such as colds and flu. In addition, animal allergies can trigger asthma attacks in susceptible people. Studies have shown that up to 67 percent of children with asthma are sensitive to animal allergens.

Direct contact with an animal is not needed to develop an allergy. Flakes from dander, saliva and urine products are extremely lightweight and easily become attached to larger particles, which can become airborne or stick to surfaces or objects. These particles remain in the environment for weeks or even months after an animal has departed.

In fact, an animal does not have to live within a home for its allergens to be present. Researchers have documented the presence of animal allergens in homes, office buildings and other environments where animals did not live. In some cases, the amount of animal allergen found was quite high. Therefore, people can experience an allergic reaction to an animal without ever having to touch it or even be near the animal.

Animal allergies may not develop quickly, and it is not unusual for animal allergies to take more than two years to develop. Allergies occur when a person’s body begins to produce a specific type of antibody called immunoglobulin E (IgE) to combat the allergen.

This process, known as sensitization, does not usually trigger allergy symptoms at first. However, when a person has become sensitized, the next exposure to the allergen can trigger an allergic reaction. The allergen comes into contact with IgE antibodies, which are attached to specialized white blood cells called mast cells. The mast cells release histamine and other chemicals that cause symptoms such as sneezing, watery eyes and coughing.

It can take weeks or even several years to create a new antibody, which is the reason why people may not be allergic to their puppy until it becomes an adult dog. In addition, puppies and kittens have no old skin to shed and therefore produce less dander. Some people may be able to tolerate baby animals but not adults. Why some people develop allergies and others do not is unknown, and research is ongoing.

One study suggests that exposure to animals during early childhood may decrease the risk of developing allergies. Researchers found that children exposed to cats or dogs during their first year of life were less than 50 percent as likely to develop animal allergies by the time they were 6 or 7 years of age.

Specific allergies are not inherited. However, a person’s risk of developing an allergy (of any type) increases if a parent has an allergy. So, a child whose parent is allergic to dog dander is more likely to develop an allergy of some type, although not necessarily to dog dander.

Some people report that they have outgrown their animal allergies once they reach adulthood. This is believed to be an illusion because once the body becomes sensitized to an animal allergen, it stays that way for life. However, symptoms can taper off in older age. The immune system weakens and the body is not strong enough to react to the same allergies it did during childhood and young adulthood.

Potential causes of animal allergies

Animal allergies are most often caused by three things: dander, saliva and urine. These are considered types of allergens because they can trigger an allergic reaction in sensitive individuals.

Dander is tiny flakes of dead skin that animals continually shed. Proteins that are secreted by oil glands in the animal’s skin are also attached to this dander. Because animals are constantly shedding dander, allergens are deposited around any area in which the animal is present. In contained areas, such as a home, the accumulation of dander is more likely to trigger an allergic reaction in people with animal allergies. However, dander is also deposited within the living environment of other animals (e.g., horses, cows) and pests (e.g., rats, mice).

With most animals, the hair or fur has nothing to do with the allergy response. A short-haired animal can cause as many allergy problems as a long-haired animal. Therefore, there is no such thing as a “hypoallergenic” pet or animal. Hairless breeds of cats, for instance, can still be highly allergenic. However, some types of animals may shed less than others, and people with mild allergies may better tolerate these animals.

Animal saliva is another primary cause of allergy symptoms – especially with animals that groom themselves frequently, such as cats. Allergens dry on the fur after grooming and then these dried substances become airborne. Since the allergens are very light, they can stay in the air a long time. They are also sticky and can adhere to furniture, walls, carpet and other textured surfaces.

Animal urine can also cause allergy symptoms – most commonly in pets with enclosed environments (such as indoor cats, guinea pigs, hamsters). An allergy-causing protein is present in the animal’s urine. As the urine dries, these allergens are released into the air and can trigger an allergic reaction.

Because different animals exude different proteins, there is not one specific protein that causes an allergic reaction. A person could therefore be allergic to mice but not to rats and vice versa.

There are other animal-related substances that may cause an allergic reaction in sensitive people. The most common, by animal, are as follows:

 SalivaDanderUrineAlbumin (a
blood protein)
DogsXX X 
Pigs  X  
Mice  XX 
RabbitsX X X
RatsX XX 

The above list is only a sample of the most common animal allergies. Many other animals (such as gerbils, horses, cattle, sheep, deer, birds, reptiles and fish) have been known to cause allergic reactions. Also, animal allergies may be triggered by products made from animals, such as wool, down jackets and comforters, feather pillows, fur coats and some upholstery.

Bird allergies are similar to other animal allergies. Allergens are released as the birds molt, preen themselves and shake feather debris into the air. Bird allergies are also associated with bird urine and droppings.

People can also be allergic to cockroach debris – material that includes outer coverings, saliva, eggs and droppings from cockroaches. Like dust mites, cockroach debris can be found in house dust and bedding.

In some people, insect bites or stings can provoke serious or life-threatening reactions (anaphylaxis). Symptoms may include extensive swelling, nausea, fatigue and fever, and anaphylaxis may include trouble breathing, hives, rapid pulse or drop in blood pressure.

People with animal allergies can safely keep pets without fur or feathers, such as fish, snakes, turtles, lizards, frogs, spiders and hermit crabs. Although fish are usually well tolerated, it is important to note that aquariums can add to the humidity in a room, resulting in an increase in mold and dust mites. An additional concern is that fish food powders are often made from seafood, a common allergen.

Related allergies and conditions

Animal allergies are related to a number of other conditions, including other allergies. People with pollen or dust mite allergies may be more likely to also have animal allergies. Also, people with outdoor allergies might experience reactions after contact with an outdoor animal, even if they do not have an animal allergy. This is because outdoor allergens such as pollen and mold can get caught in animal fur.

Specific allergies are not inherited, but the tendency to develop an allergy is inherited. If a parent is allergic to dander, for instance, a child has a higher likelihood of developing an allergy of some type, although not necessarily to dander. The risk of developing an allergy is much higher if both parents have allergies. People who are prone to develop allergies are said to be atopic.

Some of the common conditions related to animal allergies are:

  • Allergic rhinitis. An inflammation of the mucous membrane that lines the nose causing nasal congestion, sniffling and sneezing. Animal allergens can cause allergic rhinitis.

  • Allergic conjunctivitis. An inflammation of the tissue lining the inside of the eyelid that produces irritation and tearing of the eyes. Animal allergies can cause acute allergic conjunctivitis symptoms.

  • Contact dermatitis. An inflammation of the skin that is caused by direct contact with an allergen. A red, bumpy rash may appear when the skin comes into direct contact with an animal.

  • Asthma. A condition in which breathing airways become blocked or narrowed, causing shortness of breath and breathing difficulty. Animal allergens can cause acute and chronic asthma symptoms. The incidence of asthma-like symptoms in cat owners is significantly higher than those who are exposed to other animals. There is also evidence to suggest that people with animal allergies are at increased risk of developing asthma.

Signs and symptoms of animal allergies

Animal allergy symptoms are much the same as symptoms for other types of allergies. They may occur year-round and are not dependent on the seasons, like some pollen and mold allergies. People may experience one or several allergic symptoms, including:

  • Red, watery itchy eyes
  • Eczema (flaky, scaly, itchy pink patches on the skin)
  • Hives or welts
  • Watery nasal discharge
  • Sneezing
  • Sore throat
  • Coughing
  • Wheezing
  • Shortness of breath
  • Chest pain or tightness

Some people experience allergic reactions to animals within a few minutes of being exposed to them. Others may take from eight to 12 hours before their symptoms become full-blown.

The severity of allergic reactions to animals varies between patients. Rarely, some people with animal allergies experience anaphylaxis. This is a serious and possibly 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 (angioedema)
  • Lowered blood pressure

Diagnosis methods for animal allergies

Determining the specific allergen that is causing an allergic reaction can be difficult. A physician will compile a medical history and a list of symptoms in trying to diagnose an animal allergy. A physical examination will also be performed. If an animal allergy is suspected, physicians may have patients fill out a questionnaire about their frequency of exposure to animals, symptoms and possible triggers.

A patient may be asked to avoid the animal for several weeks or longer, if possible, to see if allergy symptoms subside. However, this is usually considered to be unreliable because animal dander can persist in a home for months after an animal has been removed from the home.

There are two scientific methods used to determine animal allergies: through the skin and through the blood. Because the skin is the body’s most sensitive organ, it reacts quickly to allergens. Through skin testing, usually by a prick to the skin on the arm (allergy skin test), the physician can determine if the patient is allergic to animal dander.

If a skin test for dander is negative, the physician may test for other allergens such as saliva, urine and epithelium (a type of tissue). If the test results are inconclusive, the suspected allergen may be injected beneath the skin’s surface (intradermal test) to yield better results.

In some animal allergies, reactions take the form of a skin rash and are more difficult to diagnose. A blood test called a radioallergosorbent (RAST) test takes longer to yield results, but it may be able to definitively pinpoint the allergen causing a reaction.

Treatment options for animal allergies

Treatment options for animal allergies include eliminating contact with the animal entirely (avoidance). It may take as long as six months for the dander, saliva and airborne urine allergens to dissipate to the point that they no longer cause symptoms. Therefore, people who remove a pet from the home due to allergies may not experience immediate relief. Furniture, carpets and air can harbor animal allergens for months. A thorough house cleaning, from replacing furniture to scrubbing down walls, can accelerate the process and is recommended.

Giving up a pet is an emotional issue, and many people with allergies are unwilling to take this step. Leaving an animal outside can be unsafe and unhealthy for the pet and is not usually effective for the patient. Because dander is very light and sticky, it can be carried indoors by wind or even by someone’s clothing, a process called passive transfer.

Many allergy sufferers continue to keep an animal in their home most of the time and seek other remedies. Sensitivity to animals can sometimes be lessened by immunotherapy (allergy shots). Potent antigens are administered by injection under the skin in order to desensitize the patient. This triggers the body to produce antibodies that help block the pet allergen from causing a reaction. Initially, patients are given one dose per week for several weeks or months.

Studies have shown that immunotherapy can improve but not completely prevent allergic symptoms. Cat and dog allergen immunotherapy is more successful when the patient has only occasional exposure, rather than when the animal stays in the home all of the time. In addition, immunotherapy can have potential side effects. This treatment is usually considered after medications and environmental measures have already been tried. 

There are a number of medications that people with animal allergies may use for symptom relief. Some are available over-the-counter, and others require a prescription. Patients should consult their physicians before taking any medications or supplements. Medications used in the symptom-relief of animal allergies include:

  • Steroid nose sprays.Similar to the body’s own hormones, this medication is used to lessen nasal inflammation.

  • Antihistamines. Medications that block the effects of histamines, chemicals released in an allergic reaction that produce symptoms such as runny nose and sneezing.

  • Decongestants. Medications that shrink swollen nasal tissues, which promotes easier breathing.

Although allergy medications and immunotherapy can help some people control their allergy symptoms while keeping their pets, it should be noted that individuals with severe allergies to their pets, or animal allergies that lead to asthma, must remove their pets.

In the rare instance that anaphylaxis occurs, patients will require immediate medical attention. An injection of epinephrine is required to reverse the symptoms.

Prevention methods for animal allergies

For people with animal allergies, the recommended method of preventing an allergic reaction is to completely avoid contact with the animal to which they are sensitive (avoidance).

Because people become very attached to their pets, this is not always an option for animal owners.  However, there are preventative measures that can be taken to minimize allergic reactions. They include:

  • Keep the pet out of the bedroom at all times and designate “pet-free” areas of the home, if possible.

  • Run portable air purifiers throughout the home and use a HEPA (high efficiency particulate air) filter.
  • Clean and vacuum regularly. Using a vacuum cleaner with a HEPA filter may help remove allergens.  

  • Frequently change HVAC and HEPA filters.

  • Do not permit the pet on furniture.

  • Consider placing plastic covers on upholstered furniture.

  • Remove carpeting and rugs in the home (replace with tile or hardwood flooring). People who choose to keep carpeting, or must keep it, should steam clean it frequently.

  • Avoid clutter and keep walls and floors bare.

  • Wash hands after handling the pet.

  • Avoid hugging and kissing pets.

  • Have a nonallergic individual brush the pet daily (outside), as well as bathe it twice a week.

  • Place litter boxes and animal cages away from areas of air filtration vents in homes. Also have nonallergic individuals clean soiled litter boxes and cages.

  • Provide a well-balanced diet for the pet; minimizing fur loss may reduce indoor dander.

  • Let someone else do the vacuuming to avoid breathing in allergens, or wear a mask when cleaning. Cleaning can stir animal allergens up in the air, where they are more easily inhaled.

When visiting a friend or relative who has a pet, people allergic to animals need to be particularly careful. These visits may require the allergic person to take preventative medicine before a trip or to make arrangements to sleep in a hotel.

Controlling non-pet animal allergies depends on the type of animal. Allergies caused by cockroach debris may be controlled using methods similar to those used to reduce dust mites, as well as using chemicals to kill cockroaches and cut off their food supply.

People who are allergic to insect bites or stings should, of course, avoid those animals when possible, or perform yard work at times when insects are less active. For instance, getting rid of a wasp’s nest is best done in the evening, when their activity level is low.

Some leukotriene modifiers have been used successfully to prevent the sneezing and nasal congestion associated with allergic rhinitis, an inflammation of the mucous membrane that lines the nose. Some animal allergens are known to cause allergic rhinitis. However, these medications are primarily used in people with asthma or seasonal allergies and are not specifically approved for use in the prevention of animal allergic reactions.

Questions for your doctor on animal allergies

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

  1. Do my symptoms indicate an animal allergy?
  2. What methods will you use to determine if I am allergic to animals?
  3. Will an allergy test determine which of my animals in particular is the cause of my animal allergies?
  4. I am not willing to give up my pet. What steps can I take to reduce symptoms?
  5. Are there any medicines or over-the-counter remedies that you recommend?
  6. Do I need a HEPA system in each room of my home?
  7. Is there a special shampoo I can use on my pet to reduce my allergic reactions?
  8. Can removing carpeting help alleviate my animal allergies?
  9. Are certain breeds less likely to trigger my allergy symptoms?
  10. I have had my dog for a few years. Why am I experiencing symptoms only now?
  11. Are my children likely to develop animal allergies as well?
  12. Can you recommend a pet that will not cause allergy symptoms?
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