Hair and Saliva Test for Allergies are Worthless Pseudoscience

There is a lot of mythology out there about food allergies. The recent concern about the potential risks of grain-free diets is only an issue at all because such diets became wildly popular with no evidence that grains were a problem in the first place. A lot of folks blame grains for allergies and other health problems, but there’s no real evidence this is true, and these ingredients probably play a fairly minor role in food allergies in dogs and cats.

Other myths about food allergies include the idea that changing diets can cause them (actually, prolonged exposure is usually needed to develop a sensitivity), that raw foods are less allergenic (nope, only more likely to give you a food-borne illness), and that you can use blood, hair, or saliva tests to diagnose food allergies (sorry, a limited ingredient diet trial is the only way to do this). This last misconception is perpetuated despite evidence from human medicine that it is not true because, quite frankly, it makes people money.

I’ve previously discussed an example of this quackery, Jean Dodds’ Nutriscan allergy testing system. In her book, Dr. Dodds provides many citations to support her claim that this is a legitimate test, but a cursory look at these shows they don’t make that case at all. And there are unpublished reports from at least one allergy specialist that suggest the test is not merely inaccurate but completely useless nonsense:

One veterinary dermatologist has performed her own uncontrolled test of Nutriscan, with Dr. Dodds’ knowledge and permission, and found it entirely unreliable. Twelve samples were submitted for testing in a blind manner, from dogs with known food sensitivities based on dietary testing, dogs with environmental allergies, dogs without allergic disease, and one sample of tap water. All samples including tap water, environmental allergy dogs, and normal dogs showed reactivity to beef, corn, milk and wheat. Some samples showed reactivity to soy. In some cases, these obviously false results would have led to recommendations against diets which actually helped these dogs.

Granted, this is essentially an unpublished anecdote, so while it counters the anecdotes Dodds and others put forward for Nutriscan, it is not published scientific research. Now, however, a different allergy test, using saliva and hair samples to identify allergies, has failed the same test as spectacularly as Nutriscan purportedly did.

Coyner K, Schick A. Hair and saliva test fails to identify allergies in dogs. J Small Anim Pract. October 2018. doi:10.1111/jsap.12952

Our study demonstrates that hair and saliva testing fails not only to identify allergic dermatitis in dogs, but fails to differentiate between animal and non-animal samples, providing essentially identical results, regardless of the origin of the sample.

These authors submitted not only hair and saliva from dogs with known allergies and dogs without allergies, but also fake hair samples from stuffed animals and water (in place of saliva). All of the samples tested positive for some allergies, and there was essentially no difference between the results and random chance.

Bottom Line
Saliva and hair tests for food allergies are a scam and a waste of time and money.

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9 Responses to Hair and Saliva Test for Allergies are Worthless Pseudoscience

  1. Elizabeth Andrews says:

    Finally a study to prove it’s a scam..

  2. art malernee says:

    from dogs with known food sensitivities based on dietary testing, dogs with environmental allergies, dogs without allergic disease>>>>> how was environmental allergy dx made? A lot more to dog skin allergy than elevated IGE that blood allergy testing measure.

  3. skeptvet says:

    The samples submitted for an atopic dog were from a dog diagnosed with atopy based on IDST and food trial:

    “The allergic dog was a 3-year-old, female spayed Labrador retriever. The diagnosis of food allergies had been obtained using an elimination food trial followed by single ingredient food challenges. Intradermal allergy testing had identified allergic reactions to multiple environmental allergens”

  4. MaryS says:

    Exactly as you say, I changed my dog’s food to grain-free kibble due to a allergy blood test, many years ago. He was miserable at the time, very itchy and with alopecia. Hydrolyzed kibble wouldn’t help him, only steroids would. The vet then suggested the blood test… And this is what frustrates me, being a suggestion of the vet… He tested allergic to A LOT of things (basically, he could only eat pork and fish as protein sources). I’ve found it a little weird, but I didn’t bother, because the diet change to grain-free pork- or fish-based foods worked. Now I see it was just luck. Basically, I did an elimination diet based on a false test, but I got lucky and eliminated the right ingredients! Ahah Anyway, he is now on a homemade diet, after the FDA warning about grain-free diets. Will think about designing him a few new recipes with other protein sources, now I know the test is unreliable…

  5. Louis says:

    Does it give totally random results or just false positives? If the negatives are correct, it can still be useful to select foods.

  6. skeptvet says:

    It gives positive results for some antigens for all samples, real and fake, and the pattern of which antigens are positive and which negative appears to be random, so it can’t guide clinical management.

  7. Alicia Kelly says:

    WOW! This article really useful for me. I confused for choosing the hair care and allergies care information what would be the best for everything. But review this article my confusion has cleared. Thanks a lot for sharing such an informative article about Hair and Saliva Test for Allergies and I’m sure most people can take notes from this article. One thing most people lack experience while aware of Allergies. Well, this post will give me much good ideas for allergies care. Thanks and keep it up…….

  8. Brian Lonsdale says:

    Thanks so much, been reading these articles all afternoon since I found your blog.

    Can you explain what (if any) differences there are between blood testing for environmental allergies and blood testing for food allergies/intolerance?

    I understand why blood testing for food is worthless, but I’m not sure I understand why blood testing for environmental allergies doesn’t fall under the same banner? Or do they? Doesn’t an elevated IgG response to environmental allergens just mean exposure also and not an allergic reaction?

    I have a constantly scratching GSD which my vet has had a blood test done on for environmental allergens and said that the results show an allergic response to grass, weeds, moulds and mites.

    Apparently an additional blood test will reveal exactly which grass, weeds etc. are the ones responsible – from that they can then produce vaccine shots which might help.

    At the same time, I am wondering if there are food intolerances to consider…she gets fed a raw diet at the moment and is a fairly wide variety of different proteins (we buy Nature’s Menu items). Also, I’m now thinking that food elimination testing should have been done prior to the environmental allergen testing and that hasn’t been done.

  9. skeptvet says:

    Blood testing for immunoglobulins cannot be used to diagnose atopy (environmental allergy) because, as you point out, it only indicates exposure to the antigen. Blood testing doesn’t show that a particular antigen is causing clinical signs. However, when a clinical diagnosis of atopy is made (based on clinical signs, ruling out flea and food allergies, response to therapy, etc.), blood testing may be useful in identifying antigens which are triggers for symptoms and in guiding immunotherapy. However, the evidence for this in dogs is not strong, and such testing may not always be worthwhile. Here is an evidence-based. summary of blood testing for allergies.

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