When a dog or cat is constantly scratching, licking its paws, developing ear infections, or experiencing digestive problems, finding the cause can be frustrating. Mail-in allergy tests that analyze a pet’s saliva or fur may sound like a simple solution. Unfortunately, published studies show that these tests do not reliably diagnose food or environmental allergies.
What the Studies Found
In one study, researchers submitted fur and saliva from an allergic dog and a healthy dog to a commercial allergy-testing company. They also submitted water and synthetic fur from a stuffed animal.
The test reported “allergies” in samples from the real dogs—and in the water and fake fur. The results could not reliably distinguish the allergic dog from the healthy dog or even from a toy animal. When duplicate samples were tested, the results were inconsistent. The researchers concluded that hair and saliva testing should not be used to diagnose allergies in pets. (Coyner et al., 2019)
A separate study evaluated samples from healthy animals, animals with atopic dermatitis, and control samples consisting of sterile saline and synthetic fur. Positive results were reported for every type of sample, including the saline and synthetic fur. The results for allergic animals were no different from those for healthy animals or the non-animal samples. Overall, the test performed no better than chance and was not reproducible. (Bernstein et al., 2019)
These findings raise two serious concerns:
- Poor accuracy: The test may identify allergies that do not exist.
- Poor repeatability: The same pet may receive different results when another sample is submitted.
Why Inaccurate Results Can Harm Your Pet
A long list of supposed allergies may lead an owner to eliminate many ingredients unnecessarily. This can make feeding complicated and expensive and, in some cases, create an unbalanced diet.
More importantly, relying on an inaccurate test can delay the correct diagnosis. Itchy skin and recurrent ear infections may be caused by environmental allergies, fleas, mites, bacterial or yeast infections, food reactions, or other medical conditions. Pets can also have more than one problem at the same time.
If the underlying condition is not identified and treated appropriately, the pet may continue to experience discomfort and recurring infections.
How Food Allergies Should Be Diagnosed
There is currently no dependable saliva, fur, hair, or blood test that can confirm a food allergy in dogs or cats. The accepted diagnostic method is a carefully controlled elimination diet followed by a food challenge.
During an elimination diet trial, the pet receives a veterinarian-selected hydrolyzed or novel-protein diet and no other foods, treats, flavored medications, supplements, chews, or table scraps. If the pet improves, the previous diet or individual ingredients are reintroduced to determine whether symptoms return.
Although this process takes time and requires careful compliance, it shows whether a food actually causes clinical symptoms. Current veterinary guidance continues to recognize elimination and challenge as the appropriate way to diagnose adverse food reactions. (AAHA allergy guidance)
What About Environmental Allergies?
Environmental allergy testing is different. Canine atopic dermatitis is diagnosed by evaluating the pet’s history and clinical signs and ruling out other causes of itching.
Once environmental allergy has been diagnosed, a veterinary dermatologist may perform intradermal skin testing or selected serum testing. These tests are primarily used to identify allergens for allergen-specific immunotherapy—not as stand-alone tests to prove that a pet has allergies.
The Bottom Line
Mail-in saliva and fur tests may appear convenient, but convenience is not helpful when the results are unreliable. Published studies have shown that these tests may report reactions in healthy animals, synthetic fur, and even plain saline—and may produce different results when the same animal is tested again.
If your pet is itchy or experiencing recurrent skin or ear problems, a comprehensive veterinary dermatology evaluation is the safest and most effective next step. A methodical, evidence-based approach can identify the true causes of your pet’s symptoms and lead to a treatment plan that improves comfort without unnecessary dietary restrictions.