Grain Free Food Allergy in Cats

Grain Free Food Allergy in Cats - Symptoms, Causes, Diagnosis, Treatment, Recovery, Management, Cost

What is Grain Free Food Allergy?

Grain free diets for our pets have become more common in recent years.  Although an allergy to grain in cats is rare, some felines may have a problem when consuming and digesting grains such as rice, wheat, and corn, ingredients found in many cats foods. Pet owners may feel that grains are an addition to food that is not necessary for the feline diet. However, there are many healthy cat foods available that do include these ingredients. It will be up to you and your veterinarian to determine if grain is indeed the source of the allergy that is causing symptoms for your pet.  It can be a tedious process, but if the source is discovered and removed from your cat’s diet, his prognosis of a full recovery is good.

Food allergies are becoming more of an issue in our pets.  If you suspect your cat is allergic to something in his diet, discuss it with your veterinarian.

Symptoms of Grain Free Food Allergy in Cats

Symptoms of a food allergy in your cat can include:

  • Alopecia 
  • Pruritus
  • Papules
  • Dermatitis
  • Granulomas 
  • Erythema
  • Rhinitis
  • Conjunctivitis
  • Indolent ulcers
  • Abdominal pain
  • Weight loss
  • Vomiting 
  • Diarrhea
  • Flatulence
  • Inflammatory bowel disease

Causes of Grain Free Food Allergy in Cats

A food allergy in a cat, or any other animal, is caused by a hypersensitive reaction to an ingredient or additive.  Just like an allergy in general, a food based allergy is your cat’s immune system thinking something he ingested is a threat to his body when in reality it is something harmless. In this case, your cat’s system thinks something in his grain free food is a threat and therefore the body responds in an attempt to protect itself by breaking out with skin discrepancies and gastrointestinal upset.

Diagnosis of Grain Free Food Allergy in Cats

Most veterinarians know the symptoms of a food allergy and can give a suspected diagnosis just by looking at your pet. When you arrive at the clinic, the veterinarian will begin her assessment of your cat’s symptoms by performing a full physical exam.  This will allow her to take a proper look at his symptoms and rule out possible causes of his condition based on what she sees.  

In addition to the exam, your veterinarian will also collect a verbal history from you.  She will want to know when your cat's symptoms started, if they have been progressing, if it seems to be associated with a season or not, if you have been trying to treat at home with over the counter products and so on.  All these details can help the veterinarian with her diagnosis.  She may also go into detailed analysis about your cat’s diet and environment.  She will want to know what he eats for his main food, his treats, any monthly parasitic preventions, or if you have any new air fresheners or candles in your house.  This will give her insight as to what he interacts with and is exposed to during his day to day routine.

Naturally, the veterinarian will need to rule out other possible causes of the symptoms such as gastrointestinal parasites or flea bite hypersensitivity.  These conditions can cause similar symptoms in your cat and will require some basic diagnostic testing to rule them out.  If you want to rule out environmental allergies, there is a blood serum test you can pursue if desired. 

Unfortunately there is no serum, blood, or intradermal test reliable for diagnosing food allergies.  The only way to come to a food allergy diagnosis is via a food elimination trial.  In this situation, you remove the suspected food item from your cat’s diet for a minimum of 12 weeks.  In the case of a grain free food allergy, you have to narrow it down to what ingredient you suspect the allergy is actually to and remove it.  After not eating said item, gastrointestinal signs typically resolve between 1 to 3 weeks but dermatologic symptoms take much longer to resolve as it take the skin time to heal.  If symptoms continue, then you are testing the wrong ingredient.  If symptoms resolve, then you need to confirm your suspicion by reintroducing the item into his diet.  Upon reintroduction, if his symptoms return, then you have your diagnosis.  

In the case of a grain free food allergy, you may have to cook a homemade diet for your pet if you cannot find a commercial diet to meet your needs.  It may be inconvenient, but it may also be the only way to determine what your cat’s allergy is truly is.

Treatment of Grain Free Food Allergy in Cats

There is no specific treatment for a food allergy other than to remove the culprit from your cat’s diet.  In the meantime, the veterinarian can offer supportive treatments and therapies in response to the symptoms your cat is suffering.  For example, depending on his condition, she may prescribe medications such as glucocorticoids or antihistamines to help with the itching and inflammation. If he has developed a secondary skin infection from all the scratching and lesions, she will prescribe antibiotics to address it.  Depending on your cat’s compliance and the severity of his symptoms she may recommend medication in the form of a liquid, ointment, or spray for you to administer to your cat.  

If he is experiencing any gastrointestinal upset from his allergy, your veterinarian can offer medications and therapies for it as well.  There are anti-diarrheal and anti-vomiting medications to calm your cat’s GI tract.  She may offer him injections of vitamins and administer electrolytes if she feels he needs it from all the digestive upset.  She may also send you home with supplements or probiotics in order to get his digestive system back on track.

Finding the source of your cat’s allergy is ideal.  If you are able to determine what ingredient within the grain free food is causing your cat’s symptoms and remove it from his diet, he should recover very nicely.

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Recovery of Grain Free Food Allergy in Cats

If you are unable to determine the source of the allergy, you will continuously be fighting to control your cat’s symptoms.  If you do not take the time to go through the process of a diagnosis, you will just be guessing as to what he is allergic to and likely misdiagnose it for years.  You will also have to make repetitive visits to the veterinarian for medications and therapies to ease his symptoms.  However, if you are able to discover and remove the allergy source from your cat’s diet, his prognosis of recovery is good. From diagnosis forward, all treats, supplements, and food must be verified for ingredients in order to avoid grain.

Grain Free Food Allergy Questions and Advice from Veterinary Professionals


American Shorthair




4 Years


0 found this helpful


0 found this helpful

My pet has the following symptoms:
Red Bumps
My cat since she was spade cane down with skin irritation especially on her belly. I noticed while I was feeding her grain free her belly seemed to clear up. I purchased regular cat food Blue Wilderness and her belly is red I am thinking it’s the grain in the food,

Oct. 12, 2017

0 Recommendations

It is possible that grain free food has helped clear up the skin irritation and now it has returned with the new food; the best way to test this is to switch back to the grain free for a few weeks to see if her belly clears up again, if it does clear up you’ll have your answer. Regards Dr Callum Turner DVM

Oct. 12, 2017

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