Dogs often can not tolerate soy products, wheat, corn, beef, pork, chicken, milk
, eggs, fish, chemical preservatives, or artificial sugars in their food.
Determining the food allergen can be time consuming. First, eliminate all the possible allergens from the diet, by using a home made diet consisting of a protein and a starch the dog has not eaten before. Gradually add back, one at a time for a week, the ingredients of the dog food.