Allergy to Animals (Pet Allergy)

What causes pet allergy

The immune system of an allergic person treats harmless animal proteins as a threat and makes IgE antibodies against them. On later exposure, these antibodies trigger mast cells to release histamine and other chemicals that cause symptoms.

The main allergens:

• Cats: Fel d 1, made mainly in skin glands and saliva. It is very light and sticky, stays airborne for long periods, clings to clothes and is found in homes and schools without cats.
• Dogs: Can f 1 and other proteins in dander and saliva.
• Rodents and rabbits: proteins in urine, a risk for pet owners and laboratory workers.
• Horses: proteins in dander and hair.

Fur itself is not the allergen. It carries dander and saliva, which is why "hairless" or "hypoallergenic" breeds still cause symptoms. Some individual animals shed less allergen than others, but no breed is allergen-free.

Symptoms

Nose and eyes

Allergic rhinitis and allergic conjunctivitis:

• sneezing and a runny or blocked nose
• itchy nose, mouth or throat
• red, itchy, watery eyes, sometimes with swelling
• post-nasal drip and cough
• facial pressure and poor sleep

Lungs

In people with allergic asthma, pet exposure can trigger coughing, wheezing, chest tightness and breathlessness, sometimes starting 15 to 30 minutes after exposure, or hours later.

Skin

• raised, itchy hives where a pet licked or scratched
• eczema flares in people with atopic dermatitis

Symptoms may be constant if you live with a pet, making it hard to recognize the link. They often improve after a week or more away from the animal.

Risk factors

• personal or family history of allergies, eczema or asthma
• other allergies, such as hay fever or dust mite allergy
• occupational exposure: veterinarians, groomers, lab workers, farm workers

Research suggests that growing up with a dog or cat from early infancy may lower the risk of developing pet allergy for some children, but this does not apply to children who are already allergic.

Diagnosis

An allergist will ask about symptoms, timing and exposure, and test for sensitization:

• Skin-prick test: a drop of animal allergen is pricked into the skin; a raised itchy bump within 15 minutes suggests allergy.
• Specific IgE blood test: measures antibodies to particular animal allergens and their components.
• Lung function tests if asthma is suspected.

A positive test shows sensitization; it must match symptoms on exposure to mean true allergy.

Treatment

Reducing exposure

The most effective step is avoiding the animal. If you keep a pet:

• keep it out of the bedroom at all times
• use HEPA air purifiers, especially in the bedroom
• vacuum with a HEPA-filter vacuum and replace carpets with hard floors where possible
• wash bedding and soft furnishings often in hot water
• wash your hands after touching the pet and change clothes after close contact
• bathe dogs weekly, which reduces allergen briefly
• have a non-allergic person groom the pet outdoors
• consider cat food designed to reduce Fel d 1

Medicines

• Non-drowsy antihistamines (cetirizine, loratadine, fexofenadine) for sneezing, itching and hives.
• Steroid nasal sprays (fluticasone, budesonide) used daily for congestion; they take several days for full effect.
• Antihistamine eye drops for eye symptoms.
• Decongestants short term only; avoid if you have high blood pressure or heart disease.
• Asthma inhalers as prescribed, with an asthma action plan.

Allergen immunotherapy

Allergy shots gradually desensitize the immune system to cat or dog allergens over 3 to 5 years. They can reduce symptoms and medicine use in people with persistent symptoms or asthma who cannot avoid exposure.

Complications

• poorly controlled asthma and asthma attacks
• chronic sinusitis
• sleep disturbance and reduced quality of life
• rarely, anaphylaxis, mostly after bites from rodents or high exposure in very sensitive people

Frequently asked questions

What are the symptoms of a pet allergy?

Common symptoms are sneezing, a runny or stuffy nose, itchy, watery eyes, coughing, and itchy hives where the animal touched you. People with asthma may wheeze, feel short of breath, or have chest tightness after exposure.

Are there hypoallergenic dogs or cats?

No breed is completely allergen-free. Allergens come from saliva and skin, not just fur. Some individual animals or breeds may shed less allergen, so some allergic people tolerate them better, but reactions vary widely.

Can you develop a pet allergy later in life?

Yes. Pet allergy can develop at any age, even after years of living with animals. Some people also find their allergy lessens with ongoing exposure, but this is unpredictable.

Can I keep my pet if I am allergic?

Many people do, using a combination of pet-free bedrooms, HEPA filters, cleaning, medicines and sometimes allergy shots. If you have poorly controlled asthma due to a pet, discuss the risks with your doctor.

How long do pet allergens stay in a home?

Cat allergen can remain in a home for months after the cat has gone, because it clings to furniture, carpets and walls. Deep cleaning, including carpets and upholstery, speeds removal.