Dog Allergies

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Allergies in dogs: food allergies are an irritating health problem for dogs

It's estimated that food allergies account for 10 to 15 percent of all dog allergies. A food allergy is an adverse reaction by the immune system to ingredients in the diet. This typically results in intense itching or intestinal upset.

While allergies in dogs can happen at any age, many cases are first seen in dogs under six months of age, or in those six years of age and older. Some breeds may be genetically predisposed to food allergies: Golden Retrievers, Labrador Retrievers, Cocker Spaniels, Shar-Peis, Dalmatians, Poodles, German Shepherds, Boxers and Bulldogs.

How to recognize symptoms of dog allergies

Unlike flea or environmental allergies, which are usually seasonal, food allergies tend to occur all year long. Generally, the symptoms of allergies in dogs involve either the skin or digestive systems.

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Itchiness is the most common sign of dog allergies associated with the skin and can:

  • be limited to the ears, or may extend to the face, feet, tail and abdomen
  • lead to generalized redness of the skin
  • cause secondary skin infections

Gastrointestinal symptoms in dog allergies may include:

  • excess gas
  • chronic, intermittent vomiting
  • diarrhea
  • and weight loss
Download a .pdf to learn more about food allergy and food intolerance in pets.

Understanding allergic reactions to food

A food allergy is an immune-mediated reaction. The dog produces antibodies against components of food that are normally considered harmless. This differs from a food intolerance, such as lactose intolerance, which is an adverse reaction to a food, without involvement of the immune system.

Some dogs may become allergic to a diet after just a few days, while others may eat a particular food for many years before becoming allergic.

Allergens, the components of food that stimulate an allergy, are almost exclusively protein, such as the protein found in beef, wheat, chicken and dairy. Any protein normally used in foods can cause an allergy, but the size and structure of the protein, as well as the amount of exposure the dog has to the protein can influence whether or not an allergic reaction is initiated.

Natural defenses to food allergy

Fortunately, dogs have several natural defense mechanisms that can help prevent protein from stimulating an allergic response:
  1. The digestive tract breaks protein into smaller fragments that are less likely to initiate an allergic reaction.
  2. The lining of the digestive tract acts as a physical barrier to prevent the uptake of large protein molecules.
  3. The normal immune system has a unique ability to respond to harmful substances, while remaining tolerant to dietary components.

Diagnosing allergies in dogs

There is no simple, rapid test to diagnose a food allergy, but an elimination diet feeding trial, under the direction of your veterinarian, is an effective and reliable method that can help confirm a diagnosis. It requires dedication and a significant time commitment, but if your pet shows improvement, it's well worth the effort and can help you find the best dog food for your dog's allergies.

For an elimination diet trial:
  • Feed a diet that contains a single protein and a single carbohydrate that your dog has not been exposed to before.
  • This diet must be fed exclusively for a period of 8 to 10 weeks, and possibly up to 12 weeks.
  • A hypoallergenic diet can also be used in an elimination diet trial.
If your dog's symptoms resolve during the elimination diet feeding trial, a diagnosis of food allergy is likely. The diagnosis is confirmed when your dog is fed his original diet, and the allergic symptoms reappear.

Modified protein strategy

Once the offending protein is identified, your veterinarian may recommend a hypoallergenic diet consisting of modified protein, which is less likely to elicit an allergic reaction. Essentially, the protein molecules are broken down to smaller particles and the resulting protein is considered hypoallergenic. Follow your veterinarian's directions carefully, and feed your dog only the recommended diet.