Blood and or saliva tests for food allergy appear to be inaccurate!
According to a new report by Lam A, et. al. in October 1, 2019 JAVMA, 3 companies claiming to examine saliva or blood for food allergies in dogs found that these tests often yielded positive food allergy results for dogs NOT food allergic. So saliva and serum assays are not recommended for clinical use in diagnosing food allergy in dogs. Elimination diet trials (either prescription hypoallergenic diets or supervised home cooked diets) remain the gold standard for the diagnosis of adverse food reactions in dogs.