What about Adverse Food Reactions

Your dog has been itching and scratching... or maybe he has been vomiting and has chronic diarrhea. What's causing this? Fleas? Something he's eaten? Or maybe he is having an allergic reaction to food.

Once commonly referred to as food allergy, "adverse food reaction" correctly describes a condition that affects either the skin or the gastrointestinal system or both. Food allergy is easier to say but no longer adequately describes what's going on.

"Adverse food reactions may be either an intolerance or an allergy" says a professor of dermatology in the department of veterinary clinical sciences. When the skin is affected, it is referred to as "cutaneous adverse food reaction" or CAFR.

Itchy skin may be the most frequent sign in dogs with adverse food reactions, and gastrointestinal signs, including vomiting and chronic diarrhea, are less common. Some dogs with CAFR also have or develop G.I. Symptoms.

One of the first questions veterinarians ask when presented with a patient with such symptoms is whether the itchiness is seasonal. This helps determine the cause of the itch. Itch associated with inhalant allergies and fleabite allergies is seasonal. Itch associated with CAFR is non-seasonal.

In our population of dogs in the Bangkok Metropolitan region, approximately 10 to 15 percent of dogs with non-seasonal itch have CAFR either alone or in conjunction with other allergies.

He says any area of the body can itch, including the external ears, which are considered part of the skin system since the outer ear and ear canals are lined with skin. Causes of chronic external ear infections are underlying allergies including inhalant and food reactions.

Intact, healthy skin is a barrier against both yeast and bacterial overgrowth. Skin that is inflamed or abraded from scratching due to underlying allergies, including CAFR, is no longer an effective barrier against these infections.

When a veterinarian suspects a CAFR, the next step is to confirm the diagnosis with an elimination diet trail. "At this time, elimination diets are the only way to make the diagnosis," the researcher says. "In almost all instances, it is likely to be an allergic reaction to a protein in the diet. When a carbohydrate is suspected as the source of the allergy, it may be an allergic reaction to a protein associated with the carbohydrate of the carbohydrate itself."

He says it is rare in any species to see CAFR to food additives. After the diagnosis, the owner and the veterinarian need to analyze the dog's diet history to see which protein and carbohydrate sources are the possible offenders.

The gold standard is home-cooked. However, many dermatologists usually use commercial novel protein diets. There are several prescription diets available with a wide range of protein and carbohydrate sources.

Once a diet is chosen for the trail, what's next? It is critically important to have all secondary bacterial or yeast infections under control at the time of the diet trail, as well as any concurrent flea allergy or other known skin disease. Generally, the diet trail should last at least eight weeks, but sometimes more time is needed. Diet trails fail because owners are not strict enough. Dogs continue to receive flavored tablets, supplements, snacks, treats, and table scraps....

A successful diet trail produces a happy, non-itchy dog. The dog can be "challenged" with his previous diet to see if clinical signs such as pruritus return or the dog can remain on the new diet. Each owner and veterinarian has to come up with an acceptable plan for each dog.

Similar adverse food reactions apply to dogs with gastrointestinal signs. Although the medical work-up is different, diet plays a crucial role in the diagnosis and long-term management of these dogs, too.