What Is An Allergy?
Allergies are hypersensitivity reactions to foreign substances or organisms. Anything that provokes an allergic reaction is called an allergen. Allergens can come from just about anything and signs can include scratching, stomach upsets, sneezing, rashes and other unusual behaviors.

Your veterinarian can tell the difference between an allergy and normal dog behavior. If it is an allergy, your veterinarian will try to identify the allergen and help control the signs of your dog’s allergies the best he/she can. Common categories of allergens include:

• Inhalant allergens: Allergens that are breathed in, including airborne pollen, dust and mold.
• Contact allergens: These affect a dog’s skin upon contact. Among the most common are soaps, insecticides, wool, nylon carpets and grass.
• Flea allergens: A common cause of scratching. The actual allergen is the saliva of the flea, which irritates the skin when the flea bites. Read about Fleas and Ticks.
• Food allergens: Although not common, some dogs react to ingredients in their food. See below for more on food allergies.

Food Allergies
Some dogs develop allergies to food. Food allergies usually appear as skin problems or as stomach upsets. A variety of health conditions have similar signs; therefore, your veterinarian should exclude other causes before your dog’s diet is changed.

Identifying the cause of an allergy requires detailed medical and diet history, a complete physical examination, and eliminating any other potential causes.

If a dietary ingredient is suspected to be causing a food allergy, dietary restriction according to your veterinarian’s instruction is the only way to isolate that ingredient and determine if it’s causing a problem. Restricted ingredient diets (or limited ingredient diets) should be fed for at least 2 to 3 months, and once a dog is placed on a special diet, it is important that no snacks, treats, table scraps, rawhide chews, or other dog foods be offered.

If the ingredient to which your dog is allergic can be identified, a more appropriate diet can be recommended. Diets made with “hypoallergenic” protein sources such as Purina Veterinary Diets® HA Hypoallergenic®  Canine Formula, are available. Your veterinarian may recommend one of these special diets if your dog is diagnosed with a food allergy.

Management
The goal of managing allergies is to control signs and make your dog comfortable. In most cases, avoiding the allergen does this.

In cases where the allergen can’t be identified or avoided, medications or injections may be needed to help control symptoms. Only your veterinarian can tell you the proper course.