Greetings cat lovers! Skye Blake here with some questions and answers about cat food allergies and sensitivities.
Do you think your cat has food allergies?
Could it be something else? How are allergies diagnosed?
What’s the difference between allergies and sensitivities? Let’s find out…
The information here is for general knowledge… always see your vet with questions about your cat’s individual needs.
- Who Is Skye Blake?
- What Are Food Allergies?
- Symptoms of Allergies
- Eliminate Other Allergy Sources
- What Are the Most Common Food Allergens?
- If An Allergy Is Diagnosed
- Myths About Allergy Diets
- Can Preservatives or Additives Cause Allergies?
- What Are Food Sensitivities?
- More About Cat Food
- List of Sources
Who Is Skye Blake?
Skye Blake, Cat Info Detective, is a curious cat researcher (not a veterinarian) who sniffs out expert, reliable sources about cats, studies their information, then passes it on to you!
Sometimes there’s not enough evidence for easy answers, so Skye gives you all sides, explains the situation as thoroughly and clearly as possible, and links you to experts on each page.
All sources are given at the bottom of each page so you can do more snooping…
What Are Food Allergies?
“Food allergies” are when a cat’s immune system sees a protein from a particular food as an alien invader instead of a nutrient.
It says, “Intruder alert, intruder alert!!” and goes on the attack.
Scientists don’t know yet why allergies happen in some cats and not others or what triggers the immune system to react against a nutrient it had previously accepted.
It’s possible, but rare, that there’s a reaction to a plant source but the majority of cat food allergies are to meat proteins.
No cat can develop a food allergy to an ingredient it has never eaten.
Symptoms of Allergies
Your cat feels the effects as itchy, small, pale colored fluid-filled bumps that develop on their skin.
They aren’t life-threatening, but the constant scratching can lead to sores and serious secondary bacterial infection of the skin and/or ears, along with hair loss.
In food allergies, this usually happens around a cat’s head, face and neck.
Some poor kitties have digestive reactions like vomiting, diarrhea, gassiness, and drooling, which can lead to refusal to eat, weight loss, and serious health problems.
Others end up with both skin and digestive symptoms!
Any symptoms of a food allergy happen all year round, not seasonally like pollen allergies.
They also develop over months, possibly years, becoming worse over time, and are never a sudden occurrence.
The good news is that true food allergies are rare in cats.
Eliminate Other Allergy Sources
The first thing to do if you suspect your cat has food allergies is get your cat to the vet for a complete exam and discussion about the situation.
If there’s no other medical cause for the symptoms, you’ll need to eliminate other, more common, sources of allergies.
Skin reactions are most commonly caused by flea bites, so check your cat for fleas, even if he never goes outside.
Learn more about dealing with fleas starting with “What’s a Flea? What Does It Look Like?“
Other possible environmental irritants are mold, fungi, pollen, grasses and dust mites.
Cigarette smoke, perfume, essential oils, and some cleaning products can also cause allergic reactions.
Unfortunately, all of these possible causes have similar symptoms.
Ask your vet if you should consult a veterinary dermatologist (American College of Veterinary Dermatology).
There are many possible causes of digestive reactions, so it’s best to have your vet do an evaluation to begin eliminating them.
Some possibilities are…
- eating a foreign object
- bacterial or viral infection
- food sensitivity (rather than true allergy)
This video gives helpful information you need to know about allergies…
There are tests that use hair, saliva, or blood that can be done by your vet, and you can even buy them online.
But, despite the fact that these tests are easy to use, many, if not all, have been scientifically proven to be inadequate.
They don’t accurately detect food allergies or sensitivities.
“Research results presented at a veterinary dermatology (skin) conference even showed that some tests ‘diagnosed’ plain water and stuffed animal ‘fur’ as having food allergies.”1“What every pet owner should know about food allergies” – Clinical Nutrition Service at Cummings School (tufts.edu), January 27, 2017
The Dietary Elimination Trial
The best way to diagnose food allergies is using the dietary elimination trial.
It requires dedicated, precise work from you as the cat owner, which isn’t easy… probably why the so-called “easy-to-use” ineffective tests are popular.
The dietary elimination trial requires strict adherence to a special diet you either buy through your vet or make carefully at home using a recipe developed by a board-certified veterinary nutritionist.
It’s available only through vets because it’s for special medical situations, not general long-term diets.
This diet has very few ingredients, usually one protein, one carbohydrate, and all necessary fats, vitamins and minerals.
These ingredients have to be ones your cat hasn’t ever eaten or are “hydrolyzed” (the proteins are broken down into tiny pieces that the immune system doesn’t identify).
Another possible diet to use is one that’s purified (the most likely allergens are removed).
It’s important that you work together with your vet when using this trial method.
You may have to try a few times to find something your cat will eat.
As we all know, my fellow felines can be frustratingly picky about new foods.
Discover more about dietary elimination trials at “Think Your Pet has a Food Allergy? Eliminating Mistakes in Elimination Diet Trials” – Clinical Nutrition Service at Cummings School (tufts.edu)
Steps in the Elimination Trial
There are specific steps to follow in an elimination trial.
Your vet is your partner in this situation, and you should follow all instructions carefully.
The main thing is that the special diet has to be the only food to pass your cats lips for 2-3 months, depending on the vet’s evaluation of your cat’s situation.
That means no treats, no cat toothpaste, no dental chews, no flavored anything!
The whole point is to eliminate possible allergens.
Once you’ve used this diet for the time specified by your vet, if the symptoms improve dramatically, you’ll need to confirm what food is causing the problem.
To confirm the offending ingredient(s), you have to feed the old diet and watch for the symptoms to happen again.
If they do, there’s something in that original diet that’s the problem.
In order to figure out the exact problem, the next step is to switch to the new diet.
Feeding it until the symptoms are gone is important before re-introducing ingredients.
Re-introducing has to be done one ingredient at a time and each one must be given time to see if there’s a reaction.
If you just switch diets without identifying the specific ingredient culprit, you could miss the real cause.
This happens sometimes when people switch to another diet during a seasonal change when environmental allergens, like pollen, have died down.
Unless you test each ingredient in the diet, you won’t know if it’s a true food allergy or an environmental one.
What Are the Most Common Food Allergens?
Even though true food allergies are rare in cats, the most common culprits in confirmed cases are chicken, beef, fish, egg, and dairy products, all animal proteins… NOT GRAINS.
There can be a very rare case of a cat being allergic to a plant protein product, but it’s not common at all.
Another important point is that cats do not get gluten allergies, so gluten-free diets are not appropriate for cats.
If An Allergy Is Diagnosed
What’s next if you find your cat has an allergy to certain ingredients?
You’ll have to be sure you permanently feed your cat a diet without the specific offending ingredient(s).
Talk to your vet about how to deal with the specific allergy once you’ve confirmed it.
You may want to consult a board-certified veterinary nutritionist to create a diet plan specifically for your cat.
You can find them at American College of Veterinary Nutrition.
Myths About Allergy Diets
One reason it’s important to consult your vet about a special diet is to be sure you’re getting accurate, helpful information.
There are a few myths about allergy diets are out there in cat food world.
Let’s take a look at them…
There’s no such thing as a cat food that won’t cause allergies (“hypoallergenic”).
The hydrolyzed diets you can get from your vet are the closest thing to it.
Some manufacturers sell products that say they’re for allergies, but they can’t guarantee there isn’t any residual allergen in the product from other products being processed in the same machines.
This is the same as warnings on human food labels that a product was processed where nuts or other possible allergens are processed.
Food Does Not Prevent Allergies
Feeding your cat other, more unusual proteins such as lamb, venison, duck, kangaroo, or bison does NOT prevent food allergies.
Cats can develop an allergy to any animal protein, even though it’s rare.
Rotating food constantly also doesn’t prevent food allergies.
If you do change the food frequently and your cat tolerates it, keep in mind that if your cat does develop a true allergy, none of those ingredients can be used in a dietary elimination trial.
This will severely limit what you can feed your cat while working to find the allergen.
Can Preservatives or Additives Cause Allergies?
Anything in a food product can be a possible allergen but narrowing it down to the point of proving an additive or preservative as the culprit can be very difficult.
It makes more sense to begin by eliminating the most common sources of allergic symptoms before trying to deal with less likely sources.
It’s best to discuss this further with your vet and other specialists, if needed.
What Are Food Sensitivities?
Food sensitivities (or intolerances) are different from allergies even though symptoms can be similar.
Allergies are caused by the immune system reacting to a substance, while sensitivities happen when the digestive system can’t properly break down a substance.
Some human examples are…
- breaking out in hives after eating strawberries (immune system response)
- being lactose intolerant (digestive system response)
Food sensitivities cause your cat to vomit frequently after eating or have mild diarrhea, gas, or other digestive upsets.
Some people call this a “sensitive stomach”.
Some common causes of food sensitivities are too much fat or the wrong amount of fiber.
Since there are many other possible causes for these symptoms, it’s best to take your cat to the vet to narrow down the culprit.
There are some ways you can try to determine if something in the food is causing these digestive sensitivities.
Discover more details about this at “Figuring Out Food Sensitivities“.
More About Cat Food
Now that you’ve learned a bit about food allergies, you might be curious about types of cat food, health, and nutrition.
Sources used on this website are either primary or secondary.
Primary sources are always preferable and have the most reliable information because they’re original and directly referenced.
Scientific abstracts and data are good examples of primary sources.
Secondary sources are weaker because they usually consist of opinions or articles that give no sources of their own. Sometimes they refer to primary sources.
When I use secondary sources, most are those with some authority, such as veterinarian or cat behaviorist books and articles.
List of Sources
“3 Signs Your Raw Fed Pet Might Have A Food Allergy“, Paws of Prey, April 20, 2021
“A to Z of Cat Diseases and Health Problems” by Bradley Viner, BVet Med, MRCVS, Howell Book House, New York, NY, 1998, 126-128
“Allergies in Cats” by Lauren Jones, VMD, PetMD, August 29, 2022
“Carb Confusion Part 1: The Role of Carbohydrate in Pet Foods” – Clinical Nutrition Service at Cummings School (tufts.edu)
“Cat Allergies: Learn about the Symptoms, Causes, and Treatments” by WebMD Editorial Contributors, Reviewed by Amy Flowers, DVM, February 23, 2021
“Feline Behavior: A Guide for Veterinarians” by Bonnie V. Beaver, DVM, MS, Dept. of Small Animal Medicine & Surgery, College of Veterinary Medicine, Texas A&M University, W.B. Saunders Company, Philadelphia, PA, 1992, pp. 181-184, 191
“Figuring Out Food Sensitivities” by Cailin R. Heinze, VMD, MS, DACVIM (Nutrition), Clinical Nutrition Service, Cummings School of Veterinary Medicine, Tufts University, Petfoodology, Sep 25, 2019
“Food Allergies” by Cornell University College of Veterinary Medicine
“Food Allergies in Cats” by Ryan Llera, BSc, DVM; Catherine Barnette, DVM, VCA Animal Hospital (vcahospitals.com)
“Food Allergies In Cats: Symptoms, Causes, Diagnosis & Treatment” by Pete Wedderburn, DVM, All About Cats, Updated December 1, 2022
“Research Update: Testing for Food Allergies” – by Cailin R. Heinze, VMD, MS, DACVIM (Nutrition), Clinical Nutrition Service at Cummings School (tufts.edu), March 06, 2020
“Think Your Pet has a Food Allergy? Eliminating Mistakes in Elimination Diet Trials” by Lisa M. Freeman, DVM, PhD, DACVIM (Nutrition), Clinical Nutrition Service, Cummings School of Veterinary Medicine, Tufts University, Petfoodology, April 4, 2022
“What every pet owner should know about food allergies” by Clinical Nutrition Team of Dr. Lisa M. Freeman, DVM, PhD, DACVN, Dr. Deborah E. Linder, DVM, MS, DACVN, and Dr. Cailin R. Heinze, VMD, MS, DACVN, Cummings School of Veterinary Medicine, Tufts University, Jan 27, 2017
Updated July 10, 2023