What causes allergy to animals?

We advise anyone who suffers symptoms of allergy when in contact with an animal to visit their GP, who may decide that referral to an allergy clinic is necessary. In a small number of cases, particularly among asthma sufferers, there can be the risk of a severe asthma attack. There have also been very occasional reports of the most severe, life-threatening form of allergic reaction (anaphylaxis). In such cases, avoidance of contact with the type of animal causing the problem is crucial, and referral to a specialist allergy clinic is advised.

If you have an allergy to an animal, it means you are hypersensitive to a substance produced by the animal. For example, in the case of cat allergy, the major cat allergen, known as Fel d 1, is a protein found on cat hair, produced by the sweat, salivary and anal glands. In the case of allergy to cat, dog or horse, skin flakes known as ‘dander’ also cause allergic reactions because they become merged with the animal’s saliva or urine.

Larger animals such as horses shed dander in the form of dandruff. This means you must not only avoid contact with the animal itself, but also with clothing, riding equipment or accessories that have been near horses.

Apart from cats, dogs and horses, there are other pets that produce dander and may trigger allergies for some people.  These pets include rabbits, mice, hamsters, rats, gerbils and guinea pigs. For some people, birds may also trigger reactions.


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What are the typical symptoms of animal allergy?

If you are allergic to an animal, pet allergens can trigger symptoms such as sneezing, nose or eye itching and watering, itchy rashes, and sometimes severe wheezing. If you have asthma as well as pet allergy, you may suffer asthma attacks and your lung function may worsen.

Many people mistake horse allergy for common hay fever as the symptoms can be similar and both are usually experienced outdoors.

How do you treat symptoms of animal allergy?

If allergy to animals is suspected, and especially when allergy tests confirm it, you are likely to be prescribed an antihistamine. You may also be advised to use a preventer (steroid) inhaler and nasal spray starting the day before any unavoidable exposure, for example a planned visit to a home where you know there is an animal.

For most people who don’t come into regular contact with the animal causing the problem, antihistamine tablets may be enough to relieve any passing symptoms that occur.

For those who are more severely or regularly affected, special nasal sprays designed to prevent symptoms and reduce the irritation and swelling in the nose may be prescribed.

Many people also use decongestants to help relieve a blocked nose. These come in tablet form, capsules or nasal sprays. Whilst over-the-counter decongestant nasal sprays may be helpful for occasional relief, they are not recommended for long term use as this can cause a worsening of the condition.

Emergency treatment of anaphylaxis

It is unusual to experience a severe allergic reaction or anaphylaxis from animal dander. Most significant reactions are more likely to be due to an asthma attack. Regular asthma reviews will help reduce the risk of future asthma attacks.

However, if you are at risk of anaphylaxis, you will be prescribed adrenaline auto-injectors (AAIs). You should carry two with you at all times and know how and when to use them. An AAI should be used as soon as anaphylaxis is suspected.

After an adrenaline injection is given, someone must dial 999 immediately, as symptoms may return after a short period and more than one injection may be required. The emergency service operator must be told the person is suffering from anaphylaxis (pronounced ana-fill-axis).

Animal allergy among laboratory workers

Animal allergy is an occupational risk for laboratory workers regularly exposed to lab animals and birds in the workplace. In some cases, symptoms can be severe enough to need a change of career.

On rare occasions, allergic workers have been known to suffer anaphylaxis due to bites from lab animals or from accidental puncture with needles contaminated with animal allergens. These reactions can progress rapidly and become life-threatening, so an occupational doctor may recommend the person carries AAIs. We would recommend that co-workers are trained in emergency first aid, so they can administer an AAI if required in an emergency.

All animal laboratories should have clear risk assessments in place to reduce the risk of exposure and development of animal allergy. In the UK, the Health & Safety Executive (HSE) Guidance Note EH76 offers examples of avoidance measures designed to reduce exposure.

Personal protection equipment (for example filter masks and respirators) may be helpful in reducing or preventing symptoms in affected workers. However, because tiny amounts of allergen can sometimes trigger symptoms, this may not provide complete protection.


A course of treatment known as specific immunotherapy, or desensitisation, has been successful in some people.

This approach is unlikely to be successful for people who come into regular contact with the problem animal, such as pet owners and people who are regularly exposed at their place of work. The treatment is more suitable for people who are not in contact with animals regularly.

Helpful tips

If you are allergic to your pet, you may be tempted to find a new home for it. Before reaching this decision, it is important to be allergy tested because you may be reacting to something else in the environment, such as dust or pollen. If you do find a new home for your pet, your symptoms may not improve for several months (as pet proteins take 6-9 months to degrade) unless you arrange for your carpets and upholstery to be rigorously cleaned – ideally a job for a professional.

When visiting someone with an animal that triggers your allergy, make sure you start any preventive medication in good time – and don’t forget to carry prescribed medication with you. In our view, a polite request to remove the pets from the room before you arrive is perfectly acceptable. You may still react to hair, saliva or skin flakes left on carpets and furniture.


If you keep a pet to which you are allergic, it may help to
  • right_arrow_orange_icon keep windows open whenever possible
  • right_arrow_orange_icon clean rooms regularly
  • right_arrow_orange_icon wash hands regularly
  • right_arrow_orange_icon install hardwood floors instead of carpets
  • right_arrow_orange_icon wash your pet regularly, if possible

‘Hypoallergenic’ dogs

It is a common misconception that ‘hypoallergenic’ dogs are safe for dog allergy sufferers. While it is true that some breeds produce many more allergens than others, there is none that do not produce dander or saliva, and so no breed can be classed as truly hypoallergenic. Shorter haired dogs may be preferable as they collect less dander and don’t shed as frequently, however, they are still capable of triggering an allergic reaction.

Therapy dogs in schools

Some schools have introduced therapy dogs. As animals can cause severe reactions in some children, schools should consider how allergies can be safely managed – this is preferable to excluding the use of therapy dogs altogether. A risk assessment should be carried out before introducing an animal into school to identify and reduce the risks.

Key Messages

  • right_arrow_orange_icon If you suspect you have an animal allergy, visit your GP
  • right_arrow_orange_icon If you have asthma, ensure it is well managed
  • right_arrow_orange_icon When visiting someone with an animal that triggers your allergy, start any preventive medication in good time
  • right_arrow_orange_icon Always carry prescribed medications with you
  • right_arrow_orange_icon If you are prescribed AAIs, make sure you know how and when to use them


The content of this factsheet has been peer reviewed by Dr Mich Lajeunesse, Consultant in Paediatric Allergy at Southampton Children’s Hospital.


 We are not aware of any conflicts of interest in relation to the review of this information.


 The information provided in this factsheet is given in good faith. Every effort is taken to ensure accuracy. All patients are different, and specific cases need specific advice. There is no substitute for good medical advice provided by a medical professional.


Publication Date: March 2022
Review Date: March 2025

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