Health & Nutrition | Dogs | March 26, 2020

Food Allergies and Intolerances in Dogs

Dog laying on a bed staring, does he have a food allergy?

An adverse food reaction (AFR) is a catchall phrase that can be used to describe an inappropriate response to an ingredient found in a food, often a protein. In dogs we see food intolerances and food allergies, with food allergies resulting in more severe symptoms. True allergies involve an immune system response where the body attacks the offending agent (food) and sets off a storm of physical events.

Read More: Warning signs that your pet has food sensitivities

Adverse food reactions can show up at any age, although the majority of cases first appear earlier in life. Many dogs with diagnosed food allergies also have concurrent inhalant or contact allergies (e.g. flea bite allergies).


In dogs, the symptoms of adverse food reactions are similar to those of environmental allergies and may include one or more of the following:

  • Itchy skin
  • Chronic or recurrent ear infections
  • Hair loss
  • Excessive scratching
  • Hot spots
  • Re-occurring skin infections (these many respond to antibiotics but return after they are discontinued)
  • Vomiting
  • Diarrhea

In dogs, true food allergies are rarer than the much more common intolerance. If left untreated however, a food intolerance in dogs can progress to a food allergy and potentially to the development of irritable bowel disease.


Diagnosing an adverse food reaction can be challenging. Blood and skin-patch testing are available for a number of ingredients found in pet food, however these tests are for allergies, and not intolerances. Although the testing may show which ingredients do not produce a reaction, allergy testing can provide false positives, or an incorrect result.

The “gold standard” to diagnose an adverse food reaction is a food elimination-challenge trial. This trial consists of feeding the dog a novel protein source, one that the dog has not eaten before, for at least 6-8 weeks.

GO! SENSITIVITIES Limited Ingredient Duck Recipe is an example of a diet that could be used in a food elimination trial as it includes all the nutrients that dogs require with as few ingredients as possible. Regardless of the diet used, it must be the only thing the dog eats for the 6-8 weeks. This means no treats; absolutely nothing but the special food and water. When the 6-8 weeks is up, the ingredient that was thought to create a reaction would be re-introduced. If there is then an adverse reaction, an adverse food reaction diagnosis would be confirmed.

Read More: What is the Best Way to Transition Pets to New Foods?

For many people, the “challenge” part of the food trial is not completed because once they find a food that works, there is a tendency to stick to that food. However, without the challenge, a diagnosis of adverse food reaction cannot be as definitive.

Finding out whether your dog is experiencing an adverse food reaction can be tricky, but taking the time and putting in the effort to find out can certainly help your dog lead a healthier and more comfortable life.