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Nutrition Nuggets
 
 
Your dog's nutrition is important for a healthy & happy life. petMD experts help you to know what to feed your dog, how much food to feed, and the differences in dog foods, so your dog gets optimum nutrition.
Nutrition Nuggets is the newest offshoot of petMD's Dog Nutrition Center. Each week Dr. Coates will use her expertise and wisdom to blog about the intricacies of dog nutrition.

Food Allergies Are Overdiagnosed in Dogs

December 20, 2013 / (2) comments

The term “food allergy” is overused. Owners and even some veterinarians will call any adverse reaction to a food an allergy. In some cases, the difference is primarily semantic since the most effective form of treatment is going to be avoiding the offending substance regardless of the underlying physiological reaction. But for the sake of accuracy I thought I’d talk a little about what makes a food allergy a food allergy.

 

Oftentimes, the more correct term to use is “adverse food reaction.” The American Academy of Allergy, Asthma, and Immunology puts it this way:

 

“Adverse food reaction” is a broad term indicating a link between an ingestion of a food and an abnormal response.

 

Reproducible adverse reactions may be caused by: a toxin, a pharmacological effect, an immunological response, or a metabolic disorder.

 

Food allergy is a term that is used to describe adverse immune responses to foods that are mediated by IgE antibodies that bind to the triggering food protein(s); the term is also used to indicate any adverse immune response toward foods (e.g., including cell mediated reactions).

 

I explain it to clients this way: When a dog is truly allergic to an ingredient in his food (almost always a protein), his body is misidentifying that protein as being part of an invading microorganism and launching an immune response against it. While the inflammation that results is beneficial in controlling infectious diseases or parasitism, it has only deleterious effects in the case of a food allergy.

 

In a review of 278 cases of canine food allergy, the following ingredients were most often to blame (some dogs were allergic to more than one substance, which is why the numbers below add up to more than 278):

 

Beef - 95 cases

Dairy - 55 cases

Wheat - 42 cases

Chicken - 24 cases

Egg - 18 cases

Lamb - 13 cases

Soy - 13 cases

Corn - 7 cases

Pork - 7 cases

Fish - 6 cases

Rice - 5 cases

 

Most food allergic dogs have one or more of the following symptoms:

 

  • itching, which may be localized to the face or hind end or affect most of the body
  • recurrent ear infections
  • evidence of gastrointestinal upset such as diarrhea, vomiting, or excessive gassiness

 

Obviously, none of these clinical signs are specific to food allergies or even adverse food reactions, so a thorough diagnostic work up, including a food trial with an elimination diet (one made from novel protein and carbohydrate sources) or a hydrolyzed diet is in order. If the symptoms resolve on the new diet and return when the old is reintroduced, you know the old food was to blame in some way, but you still can’t be completely sure that an allergic reaction was to blame.

 

I suspect the misdiagnosis of other types of adverse food reactions as allergies explains why food allergies are often said to have a variable response to steroids, a standard treatment for all sorts of allergic reactions. My guess is that most of the dogs who respond to steroids do have food allergies, and the ones that don’t are suffering from a non-allergic adverse food reaction.

 

Dr. Jennifer Coates

 

Image: aerogondo2 / Shutterstock

 

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Comments  2

Leave Comment
  • Makes Sense
    12/20/2013 08:46pm

    That makes tremendous sense. After all, a food allergy most likely won't cause vomiting or diarrhea.

  • 01/02/2014 12:18am

    It means that if a dog is vomiting or going through diarrhea it not always cause due to food as I always used to though that it happens due to food reaction.
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ABOUT NUTRITION NUGGETS

JENNIFER COATES, DVM

Photo of Jennifer

... graduated with honors from the Virginia-Maryland Regional College of Veterinary Medicine in 1999. In the years since, she has practiced veterinary medicine in Virginia, Wyoming, and Colorado. She is the author of several books about veterinary medicine and animal care, including the Dictionary of Veterinary Terms, Vet-Speak Deciphered for the Non-Veterinarian .

Jennifer also writes short stories that focus on the strength and importance of the human-animal bond and freelance articles relating to a variety of animal care and veterinary topics. Dr. Coates lives in Fort Collins, Colorado with her husband, daughter, and pets.

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