Food Allergies In Dogs
By Rachele Baker, DVM – Dogs can be allergic to many things including food, fleas, things floating in the air such as pollen, molds, and dust mites (atopy), or anything that touches their skin such as shampoos, carpet powders, and lawn chemicals (contact allergies). Dogs that have allergies to one thing often have allergies to other things as well. In other words, a dog may have food allergies and/or allergies to other things. In this post, we will discuss food allergies in dogs.
Food allergies tend to be non-seasonal (all year long) as opposed to allergies to airborne allergens (atopy) which are usually worse in the summer months. If your dog is excessively scratching, rubbing, and licking all year long but it seems to get worse in the summer, then he or she may have food allergies and/or other allergies.
Food allergies can develop in dogs at any age. Food allergies take time to develop and usually develop to foods that a dog has been fed for some time. The most common clinical sign of food allergies in dogs is non-seasonal itchiness. Food allergies in dogs can cause itchiness in many different areas of their bodies including their paws, ears, ventral abdomen (belly), axillae (armpits), groin, muzzle, eyes, and rectum. Dogs with food allergies may also have recurrent ear and/or skin infections.
If your veterinarian suspects that your dog may have food allergies, he or she may recommend a diet trial to see if a hypoallergenic diet or a novel protein diet will relieve your dog’s itchiness. A diet trial is considered the gold standard method of diagnosing food allergies in dogs. Blood tests for food allergies are not considered accurate for the diagnosis of food allergies in dogs. If a dog’s clinical signs improve while on the diet trial, this is indicative that they have food allergies. A diet trial is both diagnostic for food allergies and potentially therapeutic.
Diet trials can be performed with either a hypoallergenic diet or a novel protein diet. Hypoallergenic diets contain protein sources that have been broken down (hydrolyzed) into smaller molecules that are much less likely to produce an immune reaction than larger intact protein molecules. Novel protein diets contain a protein source that the dog has never eaten before. Food allergies take time to develop so the dog must have eaten a certain protein (such as beef or chicken) in the past in order to have developed an allergy to that protein. In selecting a novel protein diet, it is important to thoroughly document the foods that the dog may have eaten in the past including table scraps, treats, and flavored medications and supplements.
Dogs that have food allergies may be allergic to more than one food. In European and American dogs, beef allergy is the most common food allergy. The most common foods that cause allergies in dogs are beef, dairy products, chicken, eggs, and wheat. Feeding even a very small amount of a food that a dog is allergic to can cause a flare-up of clinical signs. In a study of dogs that were allergic to corn, the amount of corn in one single corn chip triggered a flare-up of clinical signs.
It is recommended that diet trials be continued for 8-12 weeks. During that time, it is important that you only feed your pet the hypoallergenic diet and absolutely nothing else including table scraps, rawhides, pig ears, cow hooves, flavored medications (including heartworm preventatives) or supplements, fish oils, dog biscuits or treats, flavored toothpastes, or flavored plastic toys.
If your dog is receiving a chewable heartworm preventative or other chewable medication, ask your veterinarian for a pill form of that medication. Any pills that you need to give your dog can be hidden in a small meatball formed from the canned hypoallergenic diet or novel protein diet that you are feeding your dog. It is important that dogs on diet trials not be allowed to roam so that they do not have the opportunity to get into food or garbage or get treats from the neighbors. It may also be necessary to keep your dog out of the room during meal times so that he or she does not get any foods that may have been dropped or spilled from the table.
If your dog has food allergies and you make sure to strictly adhere to the diet trial recommended by your veterinarian for eight to twelve weeks, he or she should show improvement in clinical signs. In other words, he or she should scratch, rub, and lick less frequently. However, as I mentioned above, dogs may have food allergies as well as allergies to other things so the hypoallergenic or novel protein diet alone may not completely resolve your dog’s itchiness. Make sure to schedule follow-up visits with your veterinarian and discuss these things together.