Demystifying Food Allergy

In the Northwest where parasites that cause “mange” are quite rare, itchy skin for a dog or cat is almost always a sign of allergies. Red, hairless patches, rashes and saliva-stained feet are unfortunate markers of real discomfort caused by the immune system “overdrive” in our furry friends.

Of the three types — inhalant, contact and food — the latter is one of the itchiest conditions known to companion animals. The body reacts to proteins, fillers and coloring in the food as if they were foreign invaders requiring attack. The resulting inflammation causes the skin, especially the ears, to erupt resulting in major discomfort and secondary infections.The gastrointestinal tract can also be affected leading to vomiting and abnormal stools.

Most people erroneously assume itching, due to food allergies, is brought on by a recent diet change. In fact, the opposite is true. Food allergies usually start in middle age; it requires time to develop. Most critters have been eating the now “offending” food for years without any trouble.

The biggest clues that an itchy pet has a food allergy are: he or she is free of all parasites including fleas, the condition is not seasonal (signs in both summer and winter), and a poor response to steroids is evident.

The top three allergens are beef, dairy and wheat in dogs, while cats are commonly allergic to beef, dairy and fish. Currently there is no foolproof test for food allergy other than a trial diet. There are three types of food trials: hypoallergenic, limited antigen and homemade, each of which revolve around a novel (never before seen) protein and carbohydrate in the formula.

Food trials can be tiresome and full of pitfalls that can prevent a full 8 to 10 week trial without contamination. This can be difficult as many pet owners have multiple pets to feed or have a well intentioned family member who “cheats” feeding the pet under the table. They also question whether the allergy could be a result of their pet’s chewable medication. The list goes on. The best approach is to team up with a veterinary professional. He or she can help rule in or out other types of allergies and help troubleshoot the obstacles involved with each pet's food trial. In the end, a successful food trial ends up being a win-win for everyone, including the itchy and uncomfortable pet.

Food Allergy Myths:

* Grain-free is the healthiest food for my dog or cat. As we stated above, dogs can be sensitive to wheat, but corn and soy allergies just aren't as common as beef, fish and chicken. The healthiest food for an allergic pet is one with either hydrolyzed protein (too small to be recognized by the body) or limited ingredients that he or she has never eaten.

* I can just fix the food problem by switching to another diet if it looks like my pet might have food allergy. Sadly, most pet food diets contain contaminants like “animal fat” or some sort of wheat, beef, dairy, lamb, fish or chicken. Simply changing foods will probably lead to some exposure to the same allergens.

* If my pet only gets partly better, the food trial didn't really work. Unfortunately dogs and cats can have several allergies at the same time. For example, an animal can respond initially and then relapse during a change in season because an inhalant allergy to pollen could have kicked in. The only way to determine if a response to food is real is to introduce new food in the mis when in remission. If itching restarts within two weeks, the diagnosis of food allergy is confirmed.

* Feeding “sensitive skin” food is considered a food trial. Sometimes a dog or cat with inhalant allergies will respond to a food with special ingredients, like omega-3 fatty acids, which can dampen the immune system. But not in a food allergic animal. They need novel protein and carbohydrates to shut the inflammation off.

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