Diagnosing the cause of a dog’s food allergies or food intolerances can be a matter of trial and error that involves exclusion diets and medications.

Canine food allergies and food intolerances are perhaps the most difficult pet ailments to diagnose, and the effects and symptoms of these problems can make life difficult and uncomfortable.

“Food allergies and food intolerances are usually investigated as a last resort when all other lines of investigation fail to bring up results,” explained Dr. Michael Levine, DVM, who added, “There’s no one specific test for a dog with suspected food allergies or food intolerances. Instead, it’s a matter of systematically ruling out what foods aren’t causing the problem by means of an exclusion diet. The process can take months.”

Food intolerances are different from food allergies in that the food item does not trigger an allergic response. Instead, the body simply cannot process or tolerate a food, resulting most often in chronic vomiting and diarrhea. Symptoms like dry, itchy skin and hair loss can also occur in the case of food intolerance, but they are not the result of an allergic response; instead, these symptoms arise as a result of dietary deficiencies. Dietary deficiencies are common in dogs with food intolerance problems, as the body works to expel the offending food as soon as possible, resulting in diarrhea or vomiting. This limits the amount of time the body has to absorb vitamins and nutrients, causing problems with the skin and coat and other body systems.

Symptoms of Food Allergies and Food Intolerance in Dogs

There is no one symptom that points to a food allergy or intolerance as the cause of a dog’s health problems; this is part of what makes the conditions so difficult to diagnose. Instead, there’s an array of symptoms that can be associated with a dog’s food allergy or intolerance and the symptoms can vary dramatically from case to case.

Symptoms of Food Allergies and Food Intolerance in Dogs

Symptoms of Food Allergies and Food Intolerance in Dogs

The most common signs of a dog with a food allergy or intolerance will include the following symptoms, which will usually be seen on a chronic basis:

In many cases of a dog with food allergies, the symptoms will wax and wane over time, and new symptoms may arise as other symptoms seem to improve.

Food allergies can literally arise overnight. And the allergen could be a food or ingredient that the dog has eaten without problems for years, making the situation confusing and frustrating for pet owners, who are baffled by the dog’s symptoms which arise despite no significant life changes.

Treating Food Allergies and Intolerances

Food allergies do not respond well to treatments that are often helpful for other types of allergies in dogs. A dog with food allergies will not typically respond to anti-histamine or steroid treatment, or there will be a limited improvement for a day or two before the symptoms return.

The most common treatment for a dog with food allergies or food intolerances involves an exclusion diet. An exclusion diet typically involves eliminating one ingredient at a time from the dog’s diet for a period of two weeks. This usually means serving special dog food varieties or a homemade diet until the offending food has been identified.

Treating Food Allergies and Intolerances

Treating Food Allergies and Intolerances

If, when a food item is excluded from the diet, the dog’s symptoms improve or disappear, this indicates that the food in question was causing an allergic reaction or tolerance problem. Unfortunately, multiple ingredients can be involved in food allergies and sensitivities, further complicating the process.

The most common foods known to trigger food allergies include:

  • Beef
  • Chicken
  • Eggs
  • Dairy
  • Wheat
  • Corn
  • Soy

One option available to owners of dogs with food allergies or intolerances involves serving special dog food formulas, which contain different ingredients from most other dog foods, which are typically comprised of beef, chicken, wheat, and corn. If the source of a dog’s allergy or intolerance is one of these four ingredients, switching to a new food that does not have these ingredients should alleviate the symptoms. This is typically the first approach in the case of a dog with suspected food allergies or a food intolerance.

The most common alternative food formulas used for dogs with dietary intolerance or food allergies is a lamb and rice formula, or a duck and potato formula, both of which are available in an array of brands, including Wellness, Natural Balance, Royal Canin and Science Diet.

Related Reading

Pet owners who found this article helpful may also be interested to learn more about the other causes of itchy, flaky skin in dogs and how to treat canine skin allergies. Owners of a dog with a suspected food allergy may also benefit from making a few dietary changes that will help promote overall skin health.

Control Your Pet’s Food Allergies