Understanding Pet Allergies: Key Signs and Testing

July 17, 2025Blogs

If you find yourself sneezing, wheezing, or scratching your eyes every time you visit a home with a cat or dog, you’re not alone. Pet allergies are common, but what causes them is often misunderstood. Many people assume they are allergic to pet hair, but in reality, the triggers usually lie in the microscopic proteins that animals naturally produce.

These proteins are found in pet saliva, skin flakes (dander), urine, and even oils secreted by the skin. When pets groom themselves, these proteins spread through their fur, into the air, and onto surfaces throughout the home. When inhaled or touched, they can provoke an immune response in sensitive individuals.

In this blog, we break down what really causes pet allergies, why standard tests sometimes fall short, and how advanced tools like molecular allergy testing can give you clearer answers.

What Actually Causes Pet Allergies?

Pet allergies are immune reactions to proteins found in an animal’s dander (skin flakes), saliva, urine, or serum. These proteins are called allergens. When you inhale or come into contact with them, your immune system may overreact, triggering symptoms like sneezing, nasal congestion, itchy eyes, skin rashes, or even asthma.

Each animal species has its own unique set of allergens. The most common include:

Cats: Fel d 1 (main allergen found in saliva and skin), Fel d 2 (albumin), Fel d 4 (lipocalin)
Dogs: Can f 1, Can f 2, Can f 3 (albumin), Can f 5 (found in male dog urine)
Horses: Equ c 1, Equ c 3
Guinea pigs: Cav p 1
Rabbits: Ory c 1, Ory c 2, Ory c 3

These molecules vary in structure and behavior. Some are sticky and airborne (like Fel d 1), while others are found mainly in body fluids or skin. Sensitization to one doesn’t automatically mean you’ll react to all animals, or even all breeds of the same species. That’s why testing for specific components is so useful.

Common Symptoms of Pet Allergies

Pet allergy symptoms can appear minutes after exposure—or be delayed for hours. They can be seasonal or year-round, depending on how often you’re exposed. Common symptoms include:

Sneezing and nasal congestion
Itchy, watery, or red eyes
Runny nose
Coughing or wheezing
Tightness in the chest
Shortness of breath
Itchy skin or hives
Eczema flare-ups
Asthma symptoms triggered by pet exposure

In people with asthma, exposure to pet allergens can worsen respiratory symptoms and increase the risk of attacks. Children exposed to pet allergens early in life may also be at increased risk of developing allergic asthma or rhinitis. Children and adults may also experience fatigue or brain fog due to chronic exposure and inflammation.

Why Traditional Allergy Tests Often Miss Pet Allergies

Standard allergy testing typically includes skin prick tests or total IgE blood tests using whole allergen extracts. These methods test for general pet dander rather than individual allergenic proteins. While helpful, they have limitations:

Cross-reactivity: Extracts can contain multiple proteins, including ones shared between species (like albumins or lipocalins), leading to confusing results.
Inconsistent extracts: The quality and protein content of allergen extracts can vary.
Lack of specificity: Traditional tests may only tell you that you react to “cats” or “dogs” but not which specific molecules are involved.

As a result, someone might test negative for a general “cat allergy” but still react strongly to Fel d 1, the dominant allergen in cat saliva. This can lead to underdiagnosis, misdiagnosis, or ineffective treatment plans.

In contrast, molecular allergy testing (also called component-resolved diagnostics) tests for individual allergen proteins. This reveals whether your immune system is reacting to primary allergens that cause symptoms, or just cross-reactive proteins with little clinical relevance.

Molecular Allergy Testing: The Next Generation of Allergy Diagnostics

Molecular allergy testing represents a major advancement in diagnostic precision. Rather than testing for whole pet extracts, this method evaluates IgE antibodies against specific molecular components. One of the most comprehensive examples is the ALEX² Allergy Test, which screens for over 280 allergenic molecules, including the full range of cat and dog proteins.

Benefits of Molecular Testing:

Pinpoints the exact allergen causing your symptoms
Distinguishes between primary sensitization and cross-reactivity
Helps predict the severity of allergic reactions
Supports personalized treatment plans

For example, detecting Can f 5 can explain why a patient only reacts to male dogs. Similarly, isolating Fel d 1 as the culprit helps clarify if immunotherapy or avoidance is the right path.

Cross-Reactivity: When the Source Isn’t What You Expect

Cross-reactivity occurs when your immune system reacts to similar proteins found in different sources. This means someone reacting to cat dander might also react to:

Pork (due to serum albumin shared between pigs and cats)
Dust mites or cockroaches (due to shared tropomyosins)
Other furry animals like horses, rabbits, or rodents

Molecular testing helps uncover these hidden connections. Understanding cross-reactivity ensures you don’t eliminate the wrong triggers or continue exposure to the real cause.

How to Manage Pet Allergies

Once you understand the specific allergen behind your symptoms, managing pet allergies becomes more targeted. Here are common strategies:

Environmental Controls:

Use high-efficiency particulate air (HEPA) filters
Keep pets out of bedrooms and off furniture
Wash bedding and fabrics regularly
Bathe pets frequently with allergen-reducing shampoos
Clean floors with vacuum cleaners designed for allergens

Medical Treatment:

Antihistamines to reduce sneezing and itching
Corticosteroid nasal sprays for inflammation
Leukotriene modifiers to block allergic reactions
Allergy shots (immunotherapy) tailored to specific proteins

Should You Get Tested for Pet Allergies?

Testing is recommended if you experience:

Persistent allergy symptoms around animals
Worsening asthma or breathing issues
Unclear results from previous skin or patch tests
Ongoing symptoms that don’t improve with medication
Difficulty identifying which pet or species causes the reaction

Molecular testing may be especially helpful if you:

Have conflicting results from earlier tests
Need to differentiate between multiple allergens
Are considering immunotherapy
Want to avoid unnecessary lifestyle changes (like rehoming a pet)

Additional Allergies That May Accompany Pet Sensitivities

Pet allergies often occur alongside other environmental or indoor allergens, including:

House dust mites
Mold spores
Pollen (trees, grasses, weeds)
Cockroach allergens
Latex or feathers

Comprehensive allergy testing can help reveal overlapping sensitivities that worsen symptoms or cause year-round discomfort.

When Pets Are Part of the Family: What Are Your Options?

The emotional impact of pet allergies can be significant, especially when pets are considered family members. Fortunately, many people with mild to moderate allergies can continue to live with pets using the right combination of environmental controls, medical treatment, and accurate diagnostics.

Options may include:

Identifying lower-allergen breeds (although no pet is truly hypoallergenic)
Managing protein-specific exposure
Desensitization with immunotherapy
Using biologic medications for severe allergy or asthma symptoms

Can You Be Allergic to One Animal but Not Another?

Yes. Molecular testing can show you’re allergic to cats but not dogs—or only to certain breeds or genders. It can also explain why your symptoms flare up around horses or rabbits but not around guinea pigs.

Some people react only to cross-reactive proteins, like albumins or lipocalins, which are present in multiple species. Others have true primary sensitization to one species’ unique allergen.

This nuance is essential if you’re deciding whether to keep a pet, visit certain homes, or start treatment.

FAQs About Pet Allergy Testing

Have questions about pet allergy testing? You’re not alone. Below are some of the most common concerns people have about pet allergies:

Can you be allergic to cats but not dogs?
Yes, cat and dog allergens are different proteins. It is possible to be allergic to one and not the other.
What is Fel d 1 and why is it important?
Fel d 1 is the major cat allergen, produced primarily in the salivary and sebaceous glands. It is responsible for most cat allergy reactions.
Do allergy shots work for pet allergies?
Immunotherapy can be very effective, especially when based on specific allergens identified through molecular testing.
What makes molecular testing more accurate than traditional methods?
It tests individual allergenic proteins rather than broad extracts, allowing clinicians to identify the true cause of symptoms.
Can pet allergies develop later in life?
Yes. Allergies can develop at any age, especially with increased or repeated exposure to allergens.

Finally,

Pet allergies are more nuanced than most people realize. What may seem like a reaction to fur is often an immune response to specific proteins, such as Fel d 1 in cats or Can f 5 in dogs. Traditional allergy tests may fail to detect these triggers, leaving many people without answers.

Molecular allergy testing helps clarify the picture, offering precise identification of the proteins responsible for your symptoms. By targeting the exact cause, you and your healthcare provider can craft a more effective treatment plan and make informed decisions about your environment and lifestyle.

If you’ve struggled with unexplained allergy symptoms around pets, it might be time to go beyond basic testing. With advanced diagnostics, it’s possible to live with pets and breathe easier too.