How to Diagnose Allergies – Step by Step

Allergy testing and treatment are simple when you know what to do.
The entire process takes place in several easy steps:
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1. When to Consider an Allergy Test

Testing makes sense if your animal:

• repeatedly suffers from itching, redness, or skin inflammation,
• has problems lasting more than a few weeks or that keep returning,
• does not respond to standard treatment (e.g. corticosteroids, antihistamines, shampoos),
• shows symptoms at certain times of the year (spring, summer) or after contact with specific environments (grass, dust, food).

In such cases, it is recommended to perform allergy testing and find out what triggers the reaction.

Allergy tests are most meaningful in animals older than one year. The immune system of younger animals is not yet fully developed, and the production of specific IgE antibodies (measured by the test) may be insufficient or unstable. Therefore, the results might not reflect the real allergic reaction. In puppies, kittens, or foals, allergic signs can be temporary or nonspecific. After the first year of life, the immune response is more stable, and the test provides reliable results. If symptoms appear earlier, other causes (parasites, infections, food intolerance) should be ruled out first, and testing can be done later.
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2. Sample Collection

For laboratory testing, a blood serum sample is required.

The sample is taken by a veterinarian. No special preparation is needed — the animal does not need to fast, and sampling is quick and gentle.

Ideally, the sample should be taken when the animal is not on long-term corticosteroids or strong immunosuppressants.
If that’s not possible, the veterinarian will recommend the right time. → The effect of medication on allergy testing
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When to collect the sample:

• For seasonal allergies: at least 2–4 weeks after the start of the pollen season.
• For non-seasonal allergies: at least two weeks after symptoms appear.

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Sample volume required:

• Dogs: 3 mL serum
• Cats: 3 mL serum
• Horses: 6 mL serum

A list of contraindications can be found here: Effect of medication on allergy testing

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Sample collection procedure:

Follow this procedure when collecting a sample to obtain serum from blood:

• Collect blood into a plain tube (no anticoagulant, e.g. red cap).
• Let it stand for 15–30 minutes.
• Centrifuge for 5 minutes at 4000 rpm.
• Transfer separated serum into a clean tube (e.g. screw-cap vial).
• Label the tube with the sample number, order number, client name, and animal name.
• Send to the laboratory (no refrigeration needed during transport).

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Label the test tube with serum with the sample number / order number / customer / animal name. Send the sample to the laboratory. No cooling is required during transport; this is only required during storage.

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3. Choosing the Type of Test – Screening or Complete

Before testing, it’s important to choose which test type best suits your animal.
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Screening Test

This test determines whether the animal generally has an elevated level of allergic antibodies (IgE). The result shows whether further, detailed testing is meaningful.

Recommended for:

• first suspicion of allergy,
• unclear symptoms or allergens,
• limited diagnostic budget,
• preventive screening before buying an adult animal.

If the screening test is negative, allergy is unlikely.
If positive, a comprehensive test is recommended.
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Comprehensive Test

This test measures reactions to dozens of specific allergens — mites, pollens, molds, and food components.
It defines the animal’s individual allergy profile and is essential for:

• accurate diagnosis,
• preparation of customized immunotherapy (ASIT),
• or long-term allergy monitoring.

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In short:
The screening test answers “is there an allergic process?”
The comprehensive test shows “to what exactly and to what extent.”
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4. Evaluation and Results

Results are usually available within 14 days after the sample arrives at the lab.
You will receive a clear report by email with test results and interpretation.

The report includes:

• a list of tested allergens (mites, grass, weeds, molds, animal dander, food allergens),
• measured IgE antibody concentrations for each allergen:
  negative: < 28.00 ng/mL
  positive: ≥ 28.00 ng/mL
• summary interpretation and recommendation for immunotherapy (ASIT).

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How to Interpret the Results

Interpretation is always done by a veterinarian, who will assess:

• which allergens match the clinical symptoms,
• which are clinically irrelevant,
• whether to start allergen-specific immunotherapy (ASIT).

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Accurate interpretation is key to successful treatment.
Based on the results, an individual allergen mixture is prepared for therapy.

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After the Results

The veterinarian reviews the results with the owner to decide whether to start ASIT or other targeted therapy.
Immunotherapy can be ordered by the veterinarian via email.
An individual vaccine is prepared according to the test results, and the owner receives instructions for application and care recommendations.

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5. Follow-Up and Monitoring

After diagnosis, the veterinarian:

• recommends suitable treatment or environmental adjustments,
• monitors the skin condition and overall response,
• in ASIT cases, regularly evaluates progress and adjusts medication as needed.

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6. What if the Test Is Negative but the Animal Has Symptoms

A negative allergy test does not always exclude allergy.
Possible reasons include:

• symptoms caused by other diseases (parasites, bacteria, fungi, hormonal imbalance, food intolerance),
• non-allergic itching mimicking allergy,
• immature immune system in young animals (low IgE levels),
• suppression of antibody production due to corticosteroids or immunosuppressive therapy (false negative).

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In such cases, it’s recommended to:

• repeat the test after a few months,
• add dietary elimination testing,
• or perform a dermatological examination to exclude other causes.

The allergy test is a valuable diagnostic tool, but results must always be interpreted in the context of clinical findings by the veterinarian.
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Summary – A Simple Path to Accurate Diagnosis

Veterinary consultation
Blood sampling
Laboratory analysis
Result evaluation
Start of targeted therapy