Some of the most common culprits are beef, pork, chicken, milk, whey, eggs, fish, corn, soy, wheat and preservatives. Many animals are now developing allergies to lamb as well. This was once thought to be very hypo-allergenic, but the more it is used, the more sensitivities are springing up. The first step in diagnosing a food allergy is to eliminate all possible allergens and feed ONLY a homemade diet with ingredients the dog has never eaten before. The diet should be a protein and a starch.
Good examples are one part lamb, rabbit or venison mixed with two parts rice or potatoes.
You must also keep the dog away from feces if he or she is prone to eating stool. This diet should only to be fed for a short period, while testing for allergies. It is not nutritionally complete enough for long term use. Check with your veterinarian before beginning the test. If the symptoms improve during the trial diet, go back to the original food for several days.