Canine food allergies are the third most common allergy in pet dogs, ranking behind flea allergy and inhalant allergy. It's estimated that food allergies account for 10 percent of all canine allergies.
Food allergies can develop at any time in a dog's life, although they are more common between the ages of 2 and 6 years. The clinical signs of a food allergy-scratching, skin and paw chewing, unresolved ear infections and hot spots-can develop after your dog has eaten the allergy-causing food for more than two years
What Causes Food Allergies?
Food allergies are caused by an overreaction of your dog's immune system to one or more ingredients in his diet. These ingredients are called allergens. In response to exposure to the allergen, your dog's immune system makes histamine. This chemical causes your dog's skin to become inflamed and itchy, and hives to form. Histamine may also cause a reaction in your dog's digestive tract, leading to vomiting and diarrhea.
Sifting through the Ingredients
The most common canine allergens are also ingredients that are found in many commercial pet foods. Ingredients with an allergic effect include beef, dairy products, chicken, fish, eggs, soy, wheat and corn. Preservatives and other chemicals found in some dog foods may also play a part in canine food allergies, but additional research is needed to prove or disprove a connection.
Eliminating Potential Allergens
To help determine the cause of your dog's food allergies, your veterinarian will probably recommend an elimination diet for three or four months. This diet will consist of a protein source and a carbohydrate source that is completely new to your dog. Lamb-and-rice diets were commonly used as elimination diets until pet food manufacturers began creating lamb-and-rice diets in the 1990s. Now, veterinarians use venison, rabbit or even kangaroo as protein sources, and they recommend potatoes, sweet potatoes or oats as the carbohydrate source.
Your dog needs to follow the elimination diet faithfully without treats or supplements in order to determine the source of his allergic reactions. If he is able to eat the new diet without a recurrence of allergic reactions, he has a food allergy.
Once a food allergy is determined, some owners choose to feed their dogs the elimination diet as the dog's main food. In other cases, the owner may wish to determine more fully what causes the food allergy. This means that the dog's current diet is gradually reintroduced to try to provoke an allergic reaction. Through a process of elimination, the dog owner's and his veterinarian can determine a balanced diet for the dog that does not cause allergic reactions.
Another option for owners with allergic dogs is to feed them a hydrolyzed protein diet. These diets feature protein sources that have been broken down into tiny molecules that are too small to cause an allergic reaction in sensitive dogs.