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What is a Pet Allergy?

Last updated on 10th January 2023

Pet allergies are an overreaction of the immune system to proteins in animal cells, which are usually harmless. Pet allergies are common, with up to 35% of pet owners in Britain suffering from allergy symptoms. Whilst allergies are incurable, there are a range of treatments available for pet allergies so that people can continue to own and care for their pets.

What are pet allergies?

Pet allergies refer to reactions in humans to the proteins in the animal’s skin cells, known as dander, saliva or urine of an animal. The most common pet allergies are to cats, and then to dogs. Symptoms are typically similar to those of hay fever, and allergies can develop over time as our immune system ages. You do not need to own a pet to develop a pet allergy, as you can be allergic to anyone’s pet, or develop symptoms in a home where a pet usually lives, or has visited, as pet allergens can remain in a home long after the pet has vacated it. You can also develop a pet allergy by being near someone who is carrying pet dander, for example, a work colleague or a classmate.

Pet allergy

What are the types of pet allergies?

As already mentioned, the most common pet allergies are to dogs and cats, but other pet allergies include allergies to rabbits, rodents, birds and even horses.

Cats and dogs

Whilst cats and dogs are mostly responsible for pet allergies, many cats and dogs are now being bred as hypoallergenic, meaning that they are meant to be less likely to cause allergies. However, the term ‘hypoallergenic’ is met with controversy, as, technically, all animals with fur can cause pet allergy, even if the fur is short and does not shed frequently. It is thought that the reason cats are the most cited for causing pet allergy is due to the fact that they spread their saliva through licking their fur to clean themselves.


It is not as common to be allergic to rabbits as it is to cats and dogs, but as rabbits are popular pets, allergies do occur, though they are not usually severe. As with rodents, rabbits often have hay or dust in their cage, which can exacerbate the spread of allergens.


Rodents that are typically kept as pets are gerbils, hamsters, rats, guinea pigs and mice. Additionally, rodents can trigger asthma attacks. Rodent urine is primarily responsible for allergic reactions to rodents.


Due to their feathers, birds can trigger allergic reactions by spreading feather dander when they bathe or flap their feathers.


Allergies to horses are most common in people who are in regular contact with horses, and the severity of the symptoms is highly associated with how much of the allergen the individual is exposed to.

Pets that are least likely to cause allergies are pets without fur, although reptiles are known to cause allergies as well.

What causes pet allergies?

Pet allergies are common in animals with fur, but not due to the fur itself. Animals with fur tend to clean themselves with their saliva, and fur can trap the dander that causes allergies. Pet hair can also trap other allergens, such as pollen and dust mites, which can worsen symptoms in individuals with these allergies.

When you develop an allergy, your body creates immunoglobulin E (IgE), an antibody created in response to a specific allergen, or several allergens. These antibodies seek out these allergens when they enter your body and attempt to exile them from the body by transporting them to the allergy cell, known as the mast cell, where they affix to a receptor. The mast cell responds by releasing a chemical called histamine, which is responsible for the symptoms that are characteristic of allergic reactions. Pet allergies may develop in people who are frequently exposed to certain animals, such as vets or laboratory workers.

What are the signs and symptoms of pet allergies?

Symptoms of pet allergies generally include:

  • Runny nose.
  • Sneezing.
  • Itchy skin.
  • Coughing.
  • Hives.
  • Asthma symptoms.
  • Itchy eyes.
  • Puffy eyes.
  • Watery eyes.
  • Blocked nose.
  • Itchy throat.
  • Fatigue.
  • Rash.
  • Wheezing.

Symptoms do not onset at the same time in every case. In some individuals, allergies may present immediately, or within half an hour, but for others, it can take some hours or even days for pet allergies to present.

You may also develop sinusitis, an infection of the sinus cavities, due to the consistent inflammation of the nasal passages. Sinusitis can cause pain in the head, toothache and can impair your sense of smell. It can be hard to breathe and you may have a consistently runny nose.

In very rare cases, some people may have a severe reaction, called anaphylaxis. Anaphylaxis is a severe allergic reaction, which can be life threatening, with symptoms such as shortness of breath, chest tightness, and swollen lips or airways. People with this kind of allergic reaction are usually equipped with an EpiPen, an emergency auto-injector filled with adrenaline, to counter the effects of anaphylaxis.


How are pet allergies diagnosed?

There are two main ways that an allergy can be diagnosed, which can be requested through your GP.

Skin prick test

The skin prick test is when an allergist places drops of the allergen onto an area of your skin, and then that area of the skin is lightly scratched with a thin needle so that the allergens enter the skin. Observations are made for reactions on the skin, which include skin discolouration, or a raise in the area that has been scratched, which are known as ‘wheals’. With pet allergies, reactions usually present within fifteen minutes. The allergist is able to measure the severity of the allergy by the progression of the size of the wheal.

Generally, skin prick tests are considered to be safe, although you may be advised against undergoing the test if you have ever been known to have a severe allergic reaction, such as anaphylaxis. For more serious suspected allergies, the test may be carried out in a hospital environment.

Blood test

A blood test can be performed to determine an allergy. A small sample of blood, specifically the plasma, which contains the immunoglobulin E, is tested by placing it in a dish containing the allergens. They will then measure the levels of IgE antibodies in your blood to determine the presence and severity of the allergy. This is not an instant way of finding results but is a safe way of determining allergies.

How are pet allergies treated?

Allergies are not curable, but there are many treatments available that can help to relieve the symptoms of pet allergies.

Treatments include:

Antihistamine pills

Antihistamines work by blocking the effects of the histamine that is produced in the mast cells, thus counteracting the symptoms. Antihistamines are safe to be used daily, although you should take advice from your GP before using any medication long term. Antihistamines can be taken orally or nasally, typically once a day, although some antihistamines can be taken up to three times daily. Antihistamines that are commonly used for pet allergies are chlorphenamine maleate, azelastine, desloratadine, loratadine and cetirizine hydrochloride.

As with many medications, antihistamines can have particular side effects, which include:

  • Nausea.
  • Drowsiness.
  • Sleepiness.
  • Dry mouth.
  • Headache.
  • Difficulty urinating.

You should always read the instructions when consuming any medication.


Corticosteroids, such as prednisone, are medicines that target the inflammation that is produced by the immune system’s response to the allergen.


Immunotherapy, also known as desensitisation, has been reported to have a strong success rate of long-term reduction in allergic reactions. With immunotherapy for allergies, you are injected with a low concentration of the allergen, thus exposing the body to the allergen frequently. The cells begin to decrease their sensitivity to the allergen, and the reaction becomes less severe over time. However, the outcome is not the same for every patient, and sometimes the effects of the allergy shots wear off when they stop being taken. It is unlikely that this will be offered unless the allergy is extreme.


How to manage pet allergies

As there is no ‘cure’ for pet allergies, there are ways to manage and potentially prevent symptoms as effectively as possible, including the following:

  • Avoiding pets. Whilst this is an obvious preventative measure, it can often be hard to carry out, especially if you live with a pet, or if a partner has a pet. If you have a pet, or are near one, try to avoid touching the pet directly, and set boundaries within the house about where the pet can go. Sometimes, pets can’t be avoided, such as those who have an assistance dog, like a guide dog.
  • Ensure that your pet is washed frequently. There are specific shampoos that are designed to reduce symptoms of pet allergies. You should also brush their hair and clean their bedding outside to avoid the dander being spread inside the home.
  • Clean your house frequently. To reduce the amount of dander in the home, it is recommended that you hoover or wash your house regularly, including rugs, curtains and sofas. It is recommended that you try not to have rugs and cushions if you have a pet allergy as these retain dander. Damp dusting is recommended to prevent dander from spreading, and keeping windows open can help to remove allergen particles.
  • Use an air filter. These can be effective for many allergies to rid the air of allergens.
  • Get a pet without fur. Although fur is not the cause of allergy, animals with little or no fur are least likely to cause an allergy.
  • Pre-empt contact with animals. You can take preventative measures if you know that you will be around a pet, by taking antihistamines prior.
  • Consider a new home for your pet. If your allergy becomes too difficult to live with, you may want to consider rehoming your pet. This can be a hard decision but may improve your quality of life, and the pet’s, as they will have someone who can give them the physical affection they need.
  • If you are staying in a rented home, you can ask if a pet has inhabited the home before you rent it out. Many holiday homes have a zero-pet policy.

Who can help with pet allergies?

In most cases, pet allergies are mild, and do not require anything more than antihistamines, which can often be bought over the counter. Nevertheless, some people suffer from more extreme symptoms and need to consult their GP about further treatment.

For more information about pet allergies, the following organisations may be useful:

  • Anaphylaxis UK. Anaphylaxis UK provides support and advice to anyone living with a serious allergy, including what to do in an emergency.
  • Blue Cross. Blue Cross is an animal charity that can help to find new homes for pets, as well as offer advice on how to live with a pet allergy.
  • British Lung Foundation. The British Lung Foundation offers advice on how to cope with living with allergies to prevent secondary conditions.
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About the author

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Rose Winter

Rose is a qualified teacher with six years of experience teaching in secondary schools and sixth forms across London. Before this, she worked as a communications officer in the Cabinet Office. Outside of work, Rose can be found researching topics of interest and spending time abroad.

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