A food allergy is an allergic reaction to a substance within an animal's diet. Generally, the allergen is a protein or carbohydrate source. Food allergy is strongly suspected if the first signs of itching start before the dog is six months of age or older than six years. Animals can have more than one type of food allergy.
The exact mechanism of the disease is not completely understood. Food allergies can affect the skin by causing itching and sometimes skin lesions. The ears, feet, the hollow area under the front leg at the shoulder, and groin are affected most commonly, although any part of the skin can itch. The gastrointestinal tract may react to the allergens as well; vomiting, diarrhea, and an increased number of normal bowel movements per day are typical symptoms.
An elimination diet is fed exclusively to the animal in order to diagnose definitively the food allergy. Food trials are performed to determine the allergen or multiple allergens causing the animal's reaction, so that the veterinarian can prescribe a tolerable diet. Some animals may develop new allergies with time, but their diet can be reformulated as necessary.
