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Published: Aug 14, 2012

Scratching and itching in dogs may be clinical signs of something other than fleas or a skin problem. Experts say animals that are persistently itching may be suffering from a food allergy or other type of allergy.

According to VCA Animal Hospitals, food allergies are one of the four most common types of hypersensitivities experienced by dogs. Unfortunately, allergies affect animals from all breeds and backgrounds and most commonly affect dogs over the age of 2 years.

In addition to skin reactions like itching, digestive problems such as vomiting and diarrhea, respiratory problems can also occur among dogs with food allergies. Other more subtle changes such as hyperactivity, weight loss, lack of energy and aggression may also be clinical signs of an animal with a food allergy.

One thing that dog owners should know about food allergies is that they develop over time.

"In an allergic reaction to a food, antibodies are produced against some part of the food, usually a protein or complex carbohydrate," explained veterinarian Dr. Ernest Ward on "Since antibody production is required for an allergy to develop, food allergies usually manifest after prolonged exposure to one brand, type or form of food."

Foods that are most commonly associated with allergies in dogs include dairy products, beef, lamb, chicken, chicken eggs, soy or gluten.

Diagnosing a food allergy in your pet involves feeding your dog a hypoallergenic diet for a period of eight to12 weeks. These diets consist of a limited number of ingredients.   "This special diet must not contain any ingredients that the pet has eaten in the past," explained Dr. Ward. "This also requires that no other foods, treats or supplements be fed during the trial period, including flavored medications such as vitamins or heartworm preventives."

The idea behind this diet change is to see if the itching, scratching and other clinical signs are reduced when the food the animal ingests is changed.

In some cases, a commercial diet containing foods that your dog can tolerate won't be available. When this occurs, your vet will discuss components of a home-cooked diet that is ideal for your pet.

Once your veterinarian can determine which food(s) cause a reaction in your dog, the only way to treat the allergy is to eliminate the offending foods from the animal's diet.

While food allergies are common, veterinarians warn that the effects they cause may also be associated with another disorder. This makes it crucial to visit a veterinary hospital in order to get an accurate diagnosis and to protect the health of your dog.