Food allergy is a common concern for pet owners, however, true food allergy is not very common in dogs and cats, and is a condition that is frequently over-diagnosed by veterinarians.
Food allergies account for only 10% of all pet allergies. Flea allergy and environmental allergies (called atopy) are a much more common cause of itchiness and skin problems in pets. Pets are often misdiagnosed with food allergy when what they really have is food intolerance. This is an important distinction to make. Food allergy is a TRUE allergy and a pet shows characteristic symptoms such as severe itching, hives, skin breakouts, etc. Food intolerance often causes vomiting and diarrhea and does NOT create a typical allergic response. However, whenever a pet experiences vomiting or diarrhea from a food, owners and veterinarians alike are quick to blame "food allergy".
Common food allergies:Real food allergies can strike at any age and can develop to any protein or carbohydrate in a pets food. The most common food allergens in dogs are beef, dairy products, chicken, wheat, chicken eggs, corn and soy. The most common food allergens in cats are fish, beef and dairy. You will note that these foods are the most common ingredients in standard pet foods. Therefore, these are the foods that pets are exposed to most frequently in their everyday meals. However, in order for a pet to develop a true allergy, they must not only have this chronic exposure, they must also have the genetic profile to develop an allergy.
For example, most pets eat combinations of the above ingredients EVERY MEAL, EVERY DAY, yet very few pets develop true food allergies. Again, I stress, this is not a very common condition. Adverse food reactions, however, are very common and it is hard to predict which pet will react badly to what component of a food. We know pets may react to artificial dyes, preservatives and additives in food (not to mention the gross rendered stuff)….so these are best avoided by the use of natural pet foods.
Symptoms of food allergies:Common symptoms of food allergy include itching of the face, feet, sides of the body, legs and anal area. These pets will often have yeast ear infections and skin infections that respond to antibiotics, but recur as soon as the treatment is finished. Some pets with food allergy will also have increased bowel movements and soft stool. Again, food allergies should not be confused with food intolerances which generally cause more severe vomiting and diarrhea.
Diagnosis of food allergiesIf you suspect your pet may have food allergies, contact your veterinarian. The only way to truly diagnose a food allergy is to perform a food trial with your pet. Other forms of allergy testing, such as blood and skin tests, are not reliable for diagnosing food allergy. Although you will get results from these tests, they don’t accurately correlate with food allergies present in either the dog or cat and are NOT recommended by board-certified dermatologists at this time.
For accurate diagnosis, a food trial should be performed using unique (novel) protein and carbohydrate foods to avoid possible allergens to which your pet has previously been exposed in order to "cleanse" their system of potential allergens. The “gold standard” of food trials is the home-cooked diet. The advantage of a home-cooked diet is that it is free of preservatives and other additives which can also cause allergy or intolerance in pets. Common recipes recommended include protein sources such as venison, rabbit, ostrich, buffalo, or pinto beans. Some veterinarians recommend the use of commercial hypoallergenic diets or hydrolyzed diets in which the protein source is broken down into smaller proteins so they are less allergenic. It is important to keep in mind that these smaller proteins may still be allergenic for some pets and may result in food trial failure. While many pets respond favorably to these options, some pets will not have the response they will on a home-cooked diet.
The diet trial must be conducted for 8 to 12 weeks before it can be considered successful or unsuccessful. During this time, your pet must ONLY eat the prescribed food—no table food, scraps, treats, vitamins or chewable medications (even heartworm pills) can be given during a diet trial. If a positive response is seen after this trial, your veterinarian will advise you on how to proceed.