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 cats we see food intolerances and food allergies, with food allergies resulting in more severe symptoms. True cat food allergies involve an immune system response where the body attacks the offending agent (food) and sets off a storm of physical events.

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


In cats, 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

Vomiting and diarrhea are more indicative of a food intolerance while skin issues appear to only be seen in true food allergy cases in cats. If left untreated, a food intolerance in cats can progress to a food allergy and potentially to the development of irritable bowel disease.

Read More: Warning signs that your pet has food sensitivities


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 cat food allergies, 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 a novel protein source, one that the cat 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 cats require with as few ingredients as possible. Regardless of the diet used, it must be the only thing the cat 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.

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 cat 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 cat lead a healthier and more comfortable life.


March 27, 2022 — Pet Pantry

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