When you first arrive at the veterinary clinic, the veterinarian will start with a physical exam. This will allow her to take note of all your dog’s symptoms. If your dog’s skin is irritated, the veterinarian may take a skin scraping and swab to check for external parasites or bacterial overgrowth. If your dog has watery eyes, the veterinarian may perform fluorescein staining to check for a scratch on the eye that could possibly cause the watering. They should also measure tear production to ensure it is adequate. Ears will be examined with an otoscope and any excess discharge should be sampled and examined.
Blood work will be performed to give the veterinarian a broad look as to how the internal organs are functioning and to rule out other possible causes. A complete blood count (CBC) and chemistry panel will provide the veterinarian with needed information for proper assessment. If your veterinarian feels it is necessary, she may also perform a urinalysis for further evaluation.
When it comes to diagnosis of grain allergies in dogs there are very few diagnostic tests you can run. A dietary trial is the most frequently used method. In a dietary trial, offer a diet without any grain ingredients whatsoever. During this trial, you cannot give any type of treats or flavored medication containing grains as it can affect the results. You have to feed your dog this diet for at least 90 days before you can get a reliable diagnosis. After the 90 days, if resolution of the allergic signs occurs, you then must reintroduce grains to his diet. If a relapse in allergy symptoms occurs once the grains are reintroduced, then you know the source.
Intradermal skin testing and blood tests for food allergies is not always accurate in every case. This test can give false positive and false negative results. When the result is a false positive, the dog is not allergic to the food but the test shows up positive. As for a false negative, some food allergies produce a delayed result of a positive allergic reaction and the positive diagnosis is missed. Another way the test can result in a false negative would be when the allergic response is localized. For example, if your dog is allergic to grains but symptoms only manifests as a runny nose, this means the antibodies to the allergen are located only in the nose. Since the allergens antibodies are localized in the nose and not the entire body, there are no antibodies in the bloodstream to cause a reaction throughout the rest of the body, including the skin.