Is My Cat Allergic To Her Food?

If your cat has a food allergy, it can feel like the itching never stops. 

Luckily, with the help of your vet, you can figure out the food she’s allergic to so she never has to eat it again. 

So how is it done?

The Dodo reached out to Dr. Lori Hammond, a veterinarian at the VCA Mission Animal and Bird Hospital in California, to find out how vets diagnose and treat cat food allergies — for good. 

A cat food allergy is when your cat is allergic to a specific food and has an allergic reaction whenever she eats it.

“A food allergy is a hypersensitivity reaction, usually to a type of protein,” Dr. Hammond told The Dodo. “The immune system identifies proteins within the food as allergens and creates antibodies.”

These antibodies latch onto cells in your cat’s body that release histamines and other substances that cause your cat’s allergy symptoms — which makes her get itchy (or have other reactions) whenever she eats it.

Allergies to food are more common in cats than in dogs — and cats that are Siamese (or partially Siamese) might actually be at an increased risk. 

The most common cat food allergens include beef, fish and milk and other dairy products. 

A cat can only be allergic to something she’s been exposed to before, so if she’s never eaten something — it’s actually impossible for her to be allergic to it. 

Keep in mind that your cat’s reaction might be due to a food intolerance instead of a food allergy. 

A food intolerance basically means your cat has trouble digesting a certain food, while a food allergy means your cat’s immune system plays a role in causing the reaction.

Both food intolerances and allergies have really similar symptoms, but luckily your vet can help you tell the difference between the two. 

The following are signs of food allergies in cats:

On average, cats develop food allergy symptoms when they reach around 4 to 5 years old. 

If you notice the above signs, take your cat to the veterinarian ASAP.

You can find out if your cat has food allergies with a food elimination trial, which means feeding your cat a limited diet in order to remove likely allergens from your cat’s diet. 

If your cat stops having allergic reactions during the food trial, and then starts having them again after reintroducing the trigger ingredient in the old diet, you have a confirmed food allergy.

Food elimination trials can last up to around 8 to 10 weeks. 

It’s important that you don’t give your cat any other type of food during a food trial, including table scraps and even some types of medications. “Otherwise this can confound the results,” Dr. Hammond said.

With food trials, you’d either feed your cat a limited-ingredient diet or a prescription hypoallergenic diet with a hydrolyzed (aka super digestible) protein, depending on what your vet recommends.

Limited-ingredient diets are intended to avoid common allergy triggers and contain just a few ingredients in their formulas (way fewer than what’s in your standard cat food), including an exotic protein and an atypical source of carbohydrate. These foods are typically available over the counter. 

On the other hand, hypoallergenic diets are prescription foods where the protein is specially formulated to be so small it can pass through the body undetected by the immune system. 

Your best bet, however, is to get a recommendation from your vet — especially since some diets might not be super effective for feeding trials. 

“Often diets are produced on the same equipment without appropriate cleaning in between production to prevent cross-contamination. This can lead to confounding results and would not represent a true diet trial,” Dr. Hammond said. “That is why it is so important to always work with your veterinarian when choosing the right diet for your pet.”

The best cat food for allergies is a diet that doesn’t contain the offending allergen. 

That being said, food trials to find out what the allergen is can be difficult and time-consuming — so it’s not unheard of for some pet parents to just want to keep their cats on a hypoallergenic diet indefinitely. 

“Some owners having battled signs of allergies for so long often choose to stay on the hypoallergenic diet rather than trying to determine the specific cause of the allergy,” Dr. Hammond said. 

For hypoallergenic diets, Dr. Hammond recommends Hills z/d, Royal Canin HP and Purina HA for cats, for the following reasons: 

The best treatment for your cat’s food allergies is to avoid that food altogether. So if you have the time (and patience!), a food trial for cats is 100 percent worth it.

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