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True food allergies that manifest in allergic skin disease are uncommon. This fact has not stopped a perception among many pet owners that believe that they are ever so common and often want to look at food first as the culprit for their pet’s itchiness, hair loss, and skin infections. Compounding this false perception is that reading the results of a typical blood or saliva food allergy test would lead one to believe that food allergies in dogs and cats ARE in fact common.
The reality of food allergy blood and saliva testing is that they are grossly inaccurate. The reason behind this is that the basis for allergy testing is the presence of an antibody called IgE that is unique to each individual allergen. While IgE measurement has proven to be accurate for environmental allergy testing, the opposite is true for detection of food allergens.
For reasons not fully understood, IgE production as it pertains to reactivity from food is very inconsistent as compared to IgE production to contact or inhalation allergens detected in environmental allergy blood tests. In test settings, patients have shown no real sensitivity to challenge feeding with foods showing high IgE levels in testing, while in other cases, patients have shown high reactivity when challenge fed diets with low to no IgE levels to that particular food.
Frustratingly, the only proven way to rule out or rule in food allergy is to perform a strict 12 week food trial feeding a hypoallergenic diet exclusively. Hypoallergenic diets that are chosen should be prescription level diets with strict quality control and could fall into one of two categories:
- Novel protein – Consisting of a meat source that the patient has never before been exposed to.
- Hydrolyzed protein – Diets that break up the dietary proteins into small chains that are significantly less reactive than the native large protein.
Food trials are not easy and they take time and full household cooperation, which is why they commonly fail. Both the veterinarian and the owner cannot fully guarantee in most cases if there was full household compliance with the food trial. This is especially true in homes with children or elderly grandparents that live with the family to be cared for. Yet, hypoallergenic food trial remains the only gold standard diagnostic tool at our disposal to rule in or rule out true food allergy.
The main take away from this article is to warn pet owners with allergic pets to not waste their money on food allergy blood or saliva tests.
Dr. Roger Welton is a practicing veterinarian and highly regarded media personality through a number of topics and platforms. He is the author of The Man In The White Coat: A Veterinarian’s Tail Of Love. In addition to being passionate about integrative veterinary medicine for which he is a globally recognized expert, Dr. Welton was also an accomplished college lacrosse player and remains to this day very involved in the sport. He is president of Maybeck Animal Hospital , general partner of Grant Animal Clinic, and runs the successful veterinary/animal health blogs Web-DVM and Dr. Roger’s Holistic Veterinary Care. Dr. Welton fulfills his passion for lacrosse through his lacrosse and sport blog, The Creator’s Game.