Friday, January 15, 2021

About That Allergy Test - Blood/Hair/Saliva Tests for Dietary Sensitivity

     Many owners of itchy dogs are desperate for finding relief for their fuzzy companion. The red, irritated skin is painful to see, and managing allergies can be frustrating. It can feel like no matter what you try, nothing works! While the vast majority of canine allergies are environmental, it is common for people to seek out answers in dietary sensitivities-- primarily, with the use of an allergy panel that alleges to tell you every food item triggering your pup's scratching. However, these tests are a scam. After discussing why these tests are not worth the money, we will touch on why some people find success after running them.  

    When assessing a medical test, there are a handful of things to evaluate:

Sensitivity: This measures how often a test correctly identifies the thing that it is looking for, when that thing is actually there. In other words, a high sensitivity means a low rate of false negatives. 

Specificity: This measures how often a test identifies the thing that it is looking for, rather than something else. In other words, a high specificity means a low rate of false positives. 

Accuracy: This measures how close a test comes to the bullseye on average. 

Precision: This measures how close the results land to one another when repeated, regardless of whether it's on the bullseye or not. 

Time and time again, the canine food allergy tests available on the market have been shown to have low specificity (lots of false positives), low sensitivity (lots of false negatives), low to variable accuracy, and low precision. 

Here's the research:

"Can we diagnose adverse food reactions in dogs and cats with in vivo or in vitro tests?
(August 2017) - Review of 22 abstracts and articles on the subject. Authors found low repeatability and highly variable accuracy of the tests. Concluded the reliability was too low to recommend for diagnosis. 

"Testing for food-specific antibodies in saliva and blood of food allergic and healthy dogs"
(December 2018)
- Three groups of dogs, 11 with previously diagnosed and well-managed adverse food reactions, 15 dogs with atopic dermatitis undergoing elimination diet trials, and 16 clinically healthy dogs. These dogs had Hemopet Saliva tests done and Spectrum blood tests done. This study found that clinically healthy dogs tested 'positive' (falsely) for food allergies, and generally found low specificity and low sensitivity for testing of dogs with confirmed dietary allergies. Overall, authors concluded that these tests are not diagnostic and do not offer clinical insight for management of atopic dermatitis. 

"Hair and saliva analysis fails to accurately identify atopic dogs or differentiate real and fake samples"
(January 2019) -
 Three sample groups, seven fur/saliva samples from healthy animals, six from animals with atopic dermatitis, and eleven samples of synthetic fur and sterile saline. Samples were submitted twice for each participant. Positive results were received from all samples, including synthetic fur and sterile saline. Reproducibility between duplicate samples was the same as for random chance. Common triggers were identified between both live patient samples and synthetic fur/sterile saline samples. 

"Assessment of the clinical accuracy of serum and saliva assays for identification of adverse food reaction in dogs without clinical signs of disease"
(October 2019) -
 In survey and testing of 30 client owned animals, positive results were received for healthy animals with no history of allergic food reactions, and these results were not significantly correlated with prior exposure to certain foods. Authors do not recommend clinical use of these tests. 

Why these tests yield working results for some patients:

When told about these findings, many people's reaction is to recall their own success (or a friend's success) with managing their dog's allergies or sensitivities using the results of the panel they sent off. If you look back to the diagram above, the top left target board with low accuracy and low sensitivity has one dot in the bullseye area. Even if the results are completely random, occasionally they're bound to correctly identify something. The authors of the January 2019 paper above state why this is problematic very succinctly: "The promotion and marketing of unreliable health tests to consumers can result in real harm by delaying the time to correct diagnosis and institution of appropriate treatment. Additionally, results from such tests confuse the pet owner and veterinarian and use limited financial resources that could be better applied to appropriate testing and treatment." You may restrict certain items from your dog's diet that are not triggering allergies, or you may avoid certain items and continue to experience allergies! It can become very frustrating and it takes away time and money from getting a real, accurate diagnosis. 

How to identify diet allergies:

As mentioned above, dietary allergies and sensitivities are uncommon in dogs-- they represent only about 10% of dogs with allergies. Environmental allergies, such as to fleas, pollen, or dust, are far more common causes of skin irritation and itchiness. However, if your veterinarian has cause to believe your dog's symptoms may be from diet, there is only one way to diagnose it accurately: an elimination trial. In an elimination trial, your dog will eat a diet that should not cause any allergic reaction. That means the diet has to have no proteins that your dog has previously been exposed to, since previous exposure could result in a sensitivity developing. For that reason, many vets will recommend a hydrolyzed protein diet. These diets are only available with veterinary approval, and are made in such a way that the proteins are already broken down into pieces so small, your dog's immune system is unlikely to identify and attack them (the cause of allergies). This diet is fed for 8-12 weeks, exclusively, with nothing else offered by mouth (except water). If symptoms resolve, that suggests that the problem was dietary in nature, and you can then begin to 'challenge' ingredients one at a time, by re-introducing them to your dog's diet and monitoring for a reaction. This entire process should be done under the guidance of a veterinarian. Ideally, you would be seeing a specialist, either in dermatology or nutrition. 

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Additional Resources:

Research Update: Testing for Food Allergies - Tufts Vet Nutrition

Figuring Out Food Sensitivities - Tufts Vet Nutrition

Chances Are Its Not a Food Allergy for Your Dog - TuftsYourDog

Is there a gold-standard test for adverse food reactions?

Feeding Raven Doodles - Food Allergies

Wednesday, January 13, 2021

2021 - FDA Expected to Release Further Information on DCM Investigation

UPDATE 1/26/2021: It was brought to my attention that the final version of this spending bill did not include the language below. 

 Late December, an omnibus spending bill was passed, sending out a $600 COVID stimulus check and outlining federal spending for the upcoming fiscal year. Included is the Consolidated Appropriations Act, 2021, which describes congressional directives towards agencies receiving federal funding. On page 58, the first paragraph reads: 

"FDA is directed to provide an update on the investigation it is undertaking regarding

canine dilated cardiomyopathy (DCM) and the manner in which it has released information to

the public. The update shall include: the case definition FDA uses to include or exclude cases

and the scientific work ongoing at the agency and with collaborating partners for identifying a

causation of DCM; how FDA distinguishes cases of DCM due to genetic predisposition in

certain breeds; how the agency plans to work with pet food companies and the veterinary

cardiology community during the investigation; and the timing and nature of any future public


    The FDA's investigation into this issue has been controversial, attracting frustration from pet owners, pet food industry members, pulse farmers, and veterinarians alike. Most recently, attention was drawn to a quiet update issued at a Kansas State forum revealing over 1,100 reports (up from less than 600 in 2019). The FDA later followed-up with a milquetoast release to the public that was interpreted by some industry outlets to mean the investigation was over and the diets in question were exonerated. However, the FDA has affirmed that the investigation is ongoing and diet remains a potential factor. 

    It should come as no surprise that the FDA has been hesitant to provide updates to the public. There has been significant pushback from industry members that believe the FDA's investigation is misguided and has hurt their bottom lines. Leading up to the forum, several US Senators wrote a letter to the FDA, urging that consideration be given to previous criticisms of the investigation. They write, "The investigation has been of significant interest to the pet food industry, its supply chain -which includes farmers in our states..." The criticisms in question are most likely those asserting that by naming brands and ingredients, the FDA had unjustly harmed pulse farmers and pet food manufacturers. 

    Hopefully, any additional updates released to the public will come sooner rather than later. Dr. David Edwards, Director of the Division of Animal Feeds, U.S. Food and Drug Administration, Center for Veterinary Medicine is currently scheduled to speak at the American Feed Industry Association's virtual Pet Food Conference at the end of January. It's unknown whether DCM will be mentioned at this time.

    All current evidence from the FDA's data releases and academic research outside of the FDA continue to support that there is some link between legume-rich, grain-free diets and atypical, non-hereditary dilated cardiomyopathy in dogs. The exact nature of that link remains to be seen. While many industry members wish to carry on with business as usual until the nails are in the coffin, veterinary professionals continue to recommend caution until more information is available, urging pet owners avoid implicated diet types and ingredients. There are several criteria you can use to select a food for your pet, and it is always a good idea to consult with your veterinarian as well. 

    Have questions about diet-associated DCM? Use the contact form in the side bar, comment, or email as I'm working on a comprehensive Q+A

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Further Reading on DCM:

Shady Science? DCM Research and Expression of Concern 

PFI Continues to Allow Authors to Obfuscate DCM Investigation 

FDA Quietly Issues 2020 Update on diet-associated DCM at Kansas State Forum

Troubling Industry Influence in DCM Investigation

150+ Study Analysis Shows No Link between Grain-free and DCM?" Not quite.

New Research Out of UC Davis on Diet and DCM, 2020

Should I Switch Diets? Grain-Free, DCM, and the FDA.

RE: Recent Statements on DCM via PetFoodIndustry

Is Big Business and Bad Science Behind the FDA DCM Investigation?

Rumor That The FDA Investigation is Dropping Diet

Tuesday, January 12, 2021

How To Evaluate Your Pet Food Using Ingredients List


    The ingredients list does not tell you the quality of the ingredients, the quality control processes implemented during intake and use of the ingredients, the overall digestibility or bioavailability of the diet, or the formulation of nutrients of the diet (proportion of nutrients such that the diet is complete and balanced for daily nutrition). 

    The ingredients list does not tell you the recipe. Ingredients are listed in descending order by weight prior to processing. Kibble is dried/extruded. That means that all of the water that contributes to weight of the ingredients is lost during processing, changing the final composition in terms of what remains. Meat as the first ingredient? It's mostly water, and you don't know how much more it weighed compared to the second, third, or fourth ingredient. 

    Ingredients can help you identify ingredients that your dog has a known sensitivity to (diagnosed by a diet elimination trial with a veterinarian) or identify possible ingredients of concern (such as peas or other pulse legumes). Not much else. There are better ways to evaluate your pet food. 

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Additional Resources

American College of Veterinary Nutrition: Why is the ingredient list not the way to evaluate a food for my dogs?

Tuft's Clinical Nutrition Service: Stop reading your pet food ingredient list!

Why you shouldn’t judge a pet food by its ingredient list

Feeding Raven Doodles: How to read a pet food label

"The ingredients list is important if your pet has been diagnosed with a food allergy by a veterinarian (see Food allergies for more information). Otherwise, it should not be used to make a decision when choosing a new diet."

Cat The Vet ft. NutritionRVN: Can You Judge A Pet Food On The Ingredient List? (Spoiler Alert - No!)