What is Allergy IgE Testing for Dogs and Cats? — Differences by Type and How to Choose

Skin & CoatQ&AMeongsiljang Veterinary Advisory Board

Allergy IgE testing for dogs and cats can be performed using either blood or skin samples. Here’s a clear comparison of the two methods, covering their principles, accuracy, costs, and limitations.

Why Perform Allergy IgE Testing?

A veterinarian examines a puppy’s skin while preparing for an allergy test.

Allergy IgE testing is a diagnostic tool that uses your pet’s blood or skin response to identify which specific allergens trigger an exaggerated immune reaction. The most critical step is ruling out parasitic infections, bacterial infections, and food allergies before testing. This test is only meaningful when atopic dermatitis is suspected, so it’s essential to exclude other causes of itching first to ensure accurate results.

Two Types of IgE Testing

Allergy IgE testing is primarily divided into two types: serum IgE testing (blood test) and intradermal skin testing. Serum testing involves drawing blood to measure IgE antibody levels against specific allergens, while intradermal testing involves injecting small amounts of allergens directly into the skin to visually observe any swelling reactions. Veterinary dermatology textbooks describe these two methods as complementary. Neither method alone provides a complete diagnosis.

Serum IgE Testing vs. Intradermal Skin Testing: A Comparison

Item	Serum IgE test	Intradermal skin test
Test method	Blood draw then referral to an external laboratory	Shaving the fur and injecting allergens into the skin
Anesthesia required	Not required	Sedation may be required
Test time	The blood draw is short, but results take time until the external laboratory reports back	Performed the same day, but it is a somewhat time-consuming procedure
Medication withdrawal	Discontinuing medication may be required per your veterinarian's instructions	A longer withdrawal may be required per your veterinarian's instructions
Accuracy	False positives · false negatives possible; must be interpreted together with clinical signs	Preferred when read by a dermatology specialist, but false positives · false negatives are possible
Expertise	Possible at a general clinic	A dermatology specialty clinic is recommended
Application	Possible for both dogs and cats (limited reliability in cats)	Mainly used in dogs; limited interpretation · reliability in cats

Cost, time, and accessibility vary by clinic and region.

Why Serum IgE Testing Is Convenient

Serum IgE testing is minimally invasive since it only requires a blood draw, with no need for shaving or anesthesia. However, the BSAVA Manual of Canine and Feline Dermatology notes that serum tests can yield false positives (indicating an allergy when none is present). Therefore, it is crucial to interpret results in conjunction with clinical symptoms rather than strictly adhering to them when implementing dietary restrictions. Notably, allergy tests using saliva or hair lack clinical evidence and should not be trusted.

Why Intradermal Skin Testing Is More Accurate

Intradermal skin testing is favored in dermatology because it allows direct visual assessment of the skin’s reaction, yielding high diagnostic value when interpreted by a board-certified veterinary dermatologist. The procedure involves shaving a square patch of hair on the lateral thoracic wall, injecting small amounts of various allergens sequentially, and then evaluating the degree of wheal formation after a short waiting period. However, since both types of allergy tests carry the risk of false-positive and false-negative results, they should not be used alone to confirm a diagnosis but rather interpreted alongside clinical signs. A drawback is that sedation may be required to keep the patient still during the procedure. Additionally, medications such as steroids and antihistamines can affect the results, so drugs must be discontinued for the duration specified by your veterinarian prior to testing—a period that can be difficult for pets suffering from severe itching to endure.

A veterinary dermatologist performing an intradermal skin test on a dog's side.

What to Check Before Testing

Allergy IgE testing is only meaningful after ruling out parasitic infections, bacterial infections, and food allergies first. Skipping this step can result in wasted time and money. Additionally, since steroids and antihistamines taken before the test can affect the results, it is crucial to follow the veterinarian’s instructions regarding the required withdrawal period. Abruptly stopping medication on the day of the test can be dangerous, so always consult with your vet beforehand to adjust the dosage safely.

How to Use Test Results

Allergy IgE test results are less about treatment and more about guiding management. Clinically significant positive allergens can be selected to initiate allergen-specific immunotherapy (ASIT). This therapy involves gradually increasing and periodically administering allergens to modulate the immune response. According to immunology textbooks, increasing allergen doses reduces Th2-mediated hypersensitivity reactions and lowers IgE levels. However, since atopic dermatitis is a chronic condition with no cure, the goal of immunotherapy is to reduce the intensity and frequency of itching. Individual responses vary, so consistent treatment and regular veterinary assessments are essential.

A puppy receiving allergen-specific immunotherapy injections alongside its owner.

When Is Testing Necessary?

Not all itching warrants an IgE allergy test. Atopic dermatitis is a clinically diagnosed condition that cannot be confirmed by a single test; rather, testing serves to support the diagnosis and identify specific allergens for immunotherapy. Veterinary textbooks recommend testing when symptoms persist for more than three months per year, when the side effects or efficacy of symptomatic treatments are unsatisfactory, or when the pet owner is actively considering allergen-specific immunotherapy (ASIT). If your dog experiences recurrent non-seasonal itching and other causes such as parasites, infections, or food allergies have been ruled out, testing may be worth considering. For more information on symptoms, please refer to our Dog Atopic Dermatitis Guide.

The Situation Is Different for Cats

Diagnosing skin conditions in cats differs from dogs. Textbooks note that the reliability of serum IgE testing (ASIS) in cats has not yet been fully validated, and it may not reliably distinguish between healthy cats and those with other pruritic (itchy) conditions. Therefore, feline atopic skin syndrome (FASS) is not diagnosed based on test results alone. Instead, veterinarians first rule out parasitic, fungal, and bacterial infections, as well as food allergies, before making a diagnosis based on clinical signs and response to treatment. Even when tests are performed, results must be carefully interpreted alongside clinical findings. Feline skin issues are often complex to diagnose, so consultation with a veterinary dermatologist may be necessary.

Reviewed by a veterinarian

Dr. Tony — Punnawat Phongkittirak

Veterinarian

A veterinarian who majored in veterinary medicine at Khon Kaen University, Thailand, and completed the IVSA program at North Carolina State University in the United States. Drawing on clinical experience at animal hospitals, he works in the pet healthcare field and is dedicated to building a digital care environment that connects pet parents with veterinarians.

Frequently Asked Questions

How much does an allergy IgE test cost?

The cost varies significantly depending on the clinic, location, and number of allergens tested, so it’s difficult to provide a general estimate. We recommend contacting the clinic in advance to confirm the specific tests and associated fees before your visit.

How about allergy testing using saliva or hair?

The veterinary dermatology manual states that allergy tests using samples like saliva or hair lack clinical and diagnostic validity, making it difficult to obtain meaningful results.

Do I need to do both a blood test and a skin test?

Typically, only one test is selected. However, if one result is inconclusive or if immunotherapy is being considered, both tests may be reviewed together. Since both tests play a role in diagnosis, please consult with your veterinarian to decide which approach is best.

If the test results are positive, does treatment begin immediately?

A positive test result simply identifies potential allergens; it is not a definitive diagnosis on its own. We determine the comprehensive treatment plan—including immunotherapy, environmental management, and supportive medications—based on how these results align with your pet’s clinical symptoms.

Can food allergies also be detected with an IgE test?

Food allergies cannot be reliably diagnosed with allergy tests such as serum IgE or intradermal skin testing. Veterinary textbooks explicitly state that IgE testing is not effective for diagnosing food-responsive skin diseases. Instead, the standard approach is to confirm the diagnosis through an elimination diet trial, in which the pet is fed only a single-protein or hydrolyzed diet for a set period.

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References

[1] BSAVA Manual of Canine and Feline Dermatology, 4th Edition - Allergy testing and allergen-specific immunotherapy

[2] Favrot C. et al., A prospective study on the clinical features of chronic canine atopic dermatitis and their diagnostic value, 2010

[3] Veterinary Immunology, 11th Edition - Diagnostic Criteria for Canine Atopic Dermatitis