By The Pawline veterinary teamVeterinary-reviewed by Alastair Greenway, BVM&S MRCVS · 25 July 2026
Allergen-specific IgE blood panels do not diagnose allergy — atopic dermatitis is a clinical diagnosis made by excluding other causes of itch. Their real purpose is to select which allergens to include in immunotherapy once that diagnosis is already made, which is a genuinely useful but much narrower job.
This is one of the most misunderstood tests in veterinary medicine, so the key point belongs first: an allergy blood test does not tell you whether your pet is allergic.
Allergen-specific IgE panels don't diagnose allergy — they select allergens for immunotherapy once atopic dermatitis is already diagnosed clinically.
Why the test cannot diagnose allergy
Allergen-specific IgE panels measure circulating IgE antibodies against a list of environmental allergens (pollens, moulds, dust mites). The problem is that many perfectly healthy, non-allergic dogs and cats have detectable IgE to these allergens, and some genuinely atopic animals do not. Sensitisation (having the antibody) is simply not the same as clinical allergy (reacting to it). The consequence is a test with poor specificity: run it on a healthy dog and you will very often get "positive" results.
So atopic dermatitis is a clinical diagnosis, made by taking a careful history, ruling out the other causes of itch, and seeing a characteristic pattern and distribution of disease.
What must be excluded first
Before atopy is settled on, the far more common and treatable causes of itching are excluded:
Parasites, above all fleas — flea-allergic dermatitis is extremely common and is ruled out with rigorous flea control, not a blood test. Mites (including sarcoptic mange) are also considered.
Skin infections — secondary bacterial and yeast (Malassezia) infections cause a great deal of itch and must be treated before anything is judged.
Food allergy — and here another honest limitation matters: blood and saliva tests for food allergy are not reliable. Food allergy is diagnosed only by a properly conducted elimination diet trial (a strict novel-protein or hydrolysed diet for 8 weeks, followed by rechallenge). Any test claiming to diagnose food allergy from blood or saliva should be treated with real scepticism.
What the test is genuinely for
Once atopic dermatitis has been diagnosed clinically, allergen-specific IgE testing has a real and valuable job: choosing which allergens to include in allergen-specific immunotherapy ("desensitisation"). Immunotherapy is one of the few treatments that addresses the underlying disease rather than just suppressing symptoms, and it needs a formulation tailored to the individual. Intradermal skin testing (usually by a dermatologist) is the traditional alternative and is often considered the reference method; serum IgE testing is more accessible and does not require sedation or clipping.
Cat vs dog
Atopic disease occurs in both species. In cats it is less well characterised and presents in several distinct patterns — over-grooming and hair loss, miliary dermatitis, or eosinophilic lesions — rather than the more stereotyped canine distribution. The same rules apply: clinical diagnosis first, IgE panels for immunotherapy selection, and no reliance on blood or saliva food-allergy tests. Feline eosinophils may be raised, supporting the allergic picture.
About the reference range
This page shows no range strip. Results are reported per allergen against laboratory-specific thresholds, not as a single value with a reference band, and Pawline draws a band only where it holds a verified interval. Read results against the interpretation supplied by the testing laboratory.
What to do next
If your pet is itchy, the productive path with your vet is rigorous flea control, treatment of any skin infection, and — where food is suspected — a proper elimination diet trial, not an allergy blood panel. If atopic dermatitis is then diagnosed clinically and you wish to pursue immunotherapy, that is exactly when allergen-specific IgE testing (or intradermal testing) earns its place, by defining what goes into the vaccine.
This page is educational and is not a diagnosis. Lab results are interpreted in the full clinical context by your veterinary surgeon; a single value rarely tells the whole story.
