Dietary Reactions in Cats


PetMD Editorial

Published Sep. 13, 2010

Gastrointestinal Food Reactions in Cats

Gastrointestinal symptoms due to food reactions involve abnormal symptoms to a particular diet. A cat that is experiencing a food reaction is unable to digest, absorb, or utilize a particular ingredient in the food.


It is important to note that these reactions are not due to food allergies, which involve an immune reaction to a particular component of a diet. However, both food reactions and food allergy share common symptoms, causes, diagnostics, and even treatments, making it a challenge for the attending veterinarian to differentiate between the two.


Reactions to a particular diet are often due to unknown causes, but they may be linked to a particular dietary ingredient, additive, or dietary compound. Also possible are reactions to the toxic effects of particular food contaminants (e.g., Salmonella) or to spoiled foodstuffs (e.g., mold/fungus).


Cat of any age, breed or gender can be affected. Lactose intolerance is commonly diagnosed in adult cats. Siamese and Siamese cross cats are found to be at higher risk of food sensitivities.


Symptoms and Types


Symptoms may appear after adding a new foodstuff or source to your cat's diet. The clinical symptoms may subside in the fasted state (medically supervised) or within days of a new dietary change. Common symptoms of a dietary reaction include:


  • Diarrhea
  • Vomiting
  • Flatulence/abdominal gas
  • Lack of appetite
  • Weight loss
  • Poor weight gain
  • Abdominal pain and discomfort
  • Itching/scratching excessively
  • Poor body condition




In most cases of adverse dietary reactions, there is a history of sudden diet change. The cat may also be reacting to food additives, coloring, spices, or propylene glycol, etc. Other underlying factors include an inability to utilize certain component(s) in a food and toxicity due to contaminated and/or spoiled foods.





Your veterinarian will take a detailed and comprehensive history from you, especially regarding the cat's diet. Diagnosis of food reactions can be a daunting task, as there are a number of other health problems that may produce a similar spectrum of symptoms. Moreover, there are other disorders that may occur with dietary intolerances, further complicating the diagnosis.


Laboratory tests include a complete blood count, biochemistry profile, and urinalysis. However, the results of these tests are often found normal if no other underlying disease is present. Further testing may be required to exclude other diseases that may cause similar symptoms in cats.




The most widely practiced diagnostic procedure involves dietary manipulation. In this procedure efforts are made to find out the specific culprit in the diet by minimizing the ingredients and additives. This can be done by feeding the affected cat home-cooked diets or special diet plans. Typically, within a few days of the new diet clinical symptoms will start improving in these patients. This can make it easier to determine the problematic dietary component in the individual cat. After an improvement in clinical symptoms has been confirmed, your veterinarian will try to find the particular offending ingredient by slowly adding various ingredients back into the diet.


Your veterinarian may also use endoscopy, a method in which a small camera that is attached to a flexible tube is inserted into the actual space to be examined. In this way the internal structure of the intestines can be closely examined, and will allow your doctor to take a tissue sample from the intestine for laboratory testing. Abdominal X-rays can also be useful in excluding other diseases that may cause similar clinical symptoms.




Cats with severe vomiting, diarrhea or other clinical symptoms may require hospitalization for intravenous fluid administration, antibiotics, and supportive care. In most cases, the cat does not need hospitalization.


The cornerstone of a successful treatment plan is in identifying the offending dietary component and excluding it from the diet. If the problematic dietary component cannot be identified, your veterinarian will suggest and help you plan a nutritionally complete exclusion diet. A trial and error method can be employed if a confirmatory diagnosis cannot be achieved. Your veterinarian will devise a plan to include or exclude a particular dietary component and monitor the response.


Living and Management


The prognosis of most patients is very good, especially if the offending dietary component has been identified. The major goal of therapy is to avoid the causative dietary component.


If your cat has been diagnosed with food sensitivities, you will need to avoid feeding your cat food scraps or adding new foodstuffs without first consulting with your veterinarian. If your veterinarian has prescribed a specific diet, adherence to the prescribed diet is of utmost importance.


Poor treatment response is commonly due to reduced owner compliance, such as when the cat's owner reverts to giving “treats.” Do not allow children or visitors to feed the cat without prior permission. Good owner compliance will ensure long-term improvement of the clinical symptoms.

Image: Sergey Peterman via Shutterstock

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