Dogs with food allergies usually are taken to a veterinary clinic with a history of intense licking, scratching and biting at random areas of their skin. They also often have visible skin sores, redness and patchy hair loss. These signs are fairly non-specific and are more commonly caused by flea bite hypersensitivity or by some sort of inhalant allergic reaction, similar to seasonal hay fever. The veterinarian will take a detailed history from the dog’s owner, paying particular attention to when the symptoms started, what the dog is fed and whether there have been any recent dietary changes. She will perform a thorough physical examination, keeping a lookout for any evidence of fleas or other external parasites.
If the veterinarian doesn’t find fleas, flea dirt (flea fecal material) or any other obvious source of the dog’s discomfort, she may suspect that the dog is allergic to something it is eating or coming into contact with in its immediate living environment. If the facts point to a food allergy, the doctor may recommend an elimination diet, which is the best way to identify the exact food ingredient or ingredients that trigger a dog’s food allergy. Any ingredient in commercial or homemade diets can cause an allergic reaction, depending on the particular dog’s immunological make-up. Feeding an elimination diet can be frustrating, and it can take a long time to figure out exactly what the dog is allergic to. The elimination diet protocol involves taking all commercial foods away from the dog and feeding it only one or two simple, identifiable ingredients at first – usually starting with boiled rice and chicken made from grocery store human-quality ingredients. The owner will have to watch his dog carefully to see whether its symptoms improve on this diet. If they do, he will be instructed to add only one additional item to its meals, maybe beef, lamb or corn. If the itchiness still doesn’t recur, then the dog isn’t allergic to any of those ingredients. One by one, additional foods will be added to its meals, until the itching, scratching and other symptoms return and the culprit is identified.
Dogs can be allergic to more than one component of their diet. The owner must be religious about keeping his dog away from table scraps and access to any other ingestible items during an elimination diet. All treats should be withheld. The foods fed during this process should not contain food coloring, preservatives, fancy flavorings or other processed additives. They should be pure ingredients, so that the dog’s owner and veterinarian can accurately pinpoint which part of the diet triggers the allergy. Usually, the allergen is a meat or some other protein source, although corn or other items can also cause hypersensitivity reactions. Once it is identified, the allergen should be removed from the dog’s diet, and its symptoms should quickly resolve. Fortunately there are an increasing number of commercially-available kibbles that contain novel protein sources, such as venison, buffalo, rabbit and duck. Owners of dogs with food allergies have a wide selection of dog foods to choose from and rarely will need to feed a homemade diet to enhance their dogs’ quality of life.