What Is Food Intolerance in Pets? A Complete Guide

What Is Food Intolerance in Pets? A Complete Guide

Oh, the life of a pet! Many things in a pet’s life are routine, so when a new food is introduced into its diet and your precious pooch gets sick, you know that the problem was obviously in the food. Cats and dogs can’t tell us what is making them sick (boy, don’t we wish they could talk?), so it’s our responsibility as their “fur parents” to find out what foods aren’t being tolerated by your furry friends.

So, what is food intolerance? How does it differ in pets versus humans? And how do you test for it? Not to worry - we’ve got your back! Together, we’ll explore what a food intolerance looks like in an animal, what’s happening with your pet, and how you can keep your most loyal companion from getting sick in the future.

Although most people use the terms ‘food allergies’ and ‘food intolerance’ interchangeably, they actually mean completely different things. Food allergies, or sensitivities, are adverse reactions to the food where your immune system attacks the cells because it recognizes the food as a foreign invader in the body. Your, or your pet’s, immune system fights against the allergen and causes an allergic reaction.

Food intolerance, on the other hand, encompasses all kinds of bad reactions to foods, but not the allergic kind. Food intolerance covers a diverse category of reactions that often begins in the stomach or intestines when the body is not comfortable with or can’t handle whatever was eaten.

What Does Pet Food Intolerance Look Like?

We never want our furry friends to be uncomfortable, so spotting a food intolerance is crucial to helping them live their best life. Food intolerance looks different in animals depending on their species and the type of food consumed, but there are some universal signs that you, their beloved owner, can be on the lookout for. Some of the symptoms you may see if your pet isn’t tolerating a food well can include:

  • Diarrhea
  • Vomiting
  • Excessive gas
  • Lack of appetite
  • Weight loss / Poor weight gain
  • Abdominal pain or discomfort
  • Itching or scratching
  • Poor body condition


Keep in mind that these symptoms can also indicate other types of health problems besides food intolerance, so it’s important to work with your pet’s veterinarian to rule out other illnesses or issues before checking for food intolerance. Trust us - we completely understand that your fur baby’s health is a top priority!

What Can Cause Food Intolerance?

There are several factors that can contribute to your pet’s development of a food intolerance. Here are some of those factors that you and your vet should explore as potential causes for possible food intolerances.


No one likes bacteria! Although food spoiling isn’t usually an issue for cats and dogs, the bacteria that results from it can result in an illness, even in an otherwise healthy adult cat or dog. Companion animals are at high risk for aflatoxicosis due to Aspergillus, which contaminates grains and legumes. In addition, penicillium, another bacterium, despite being a key ingredient in making medicine for humans, is especially toxic in dogs. It can even cause them to have seizures if they eat moldy foods!

Oily fishes, such as anchovies, tuna, and sardines, when left to mold and accumulate bacteria, can cause seafood poisoning in both cats and dogs. We know that cats love fish, but, if you’re going to give Mr. Mittens some fish, make sure it’s “oh-so-fresh” fish.

Certain Foods

There are certain types of food that some animals should avoid eating at all costs. Remember, humans and animals digest and process food very differently, so just because it’s good for you, doesn’t mean it’s good for them. For example, in dog food, protein from beef, dairy products, and wheat can all cause negative reactions like food intolerance in your pup.

Both cooked and raw onions, garlic, leeks, and chives are all very toxic to dogs and cats. They can cause gastrointestinal issues and problems with the heart that are very unpleasant and possibly even fatal for your best buddy. You should also keep an eye on foods that contain vitamins A and D since ingesting too much of those can also cause food poisoning in your pets. Who knew, right?


Got a green thumb? While you might enjoy caring for indoor and outdoor plants, you may need to consider keeping them out of your pet’s reach. It’s only natural to enjoy a lush, beautiful garden, but your curious kitty might accidentally eat something that doesn’t agree with their little body. Tulips specifically are toxic to dogs, cats, and horses, so make sure that you keep your pets separate from your precious garden just to be safe.

Additives and Other Substances

Few studies have addressed the toxic effects of additives on pets introduced during food manufacturing, but it is clear that some of those additives can be responsible for problems. One of the main additives we’re talking about is called disulfide which is naturally found in onions and is the reason your animals can’t ingest them.

Type of Breed

Your pet’s breed may also be a factor in the development of food intolerance. Some dog breeds like West Highland White Terriers, Cocker Spaniels, and Irish Setters are more likely to develop food intolerances. Cat owners have noticed the same trend among Siamese cats. So, it’s always good to do some research on your furry friend’s breed and history to see what you should be on the lookout for.

How Do I Find Out What Caused My Pet’s Intolerance?

According to the Pet Food Institute , one of the best ways to find what causes an animal’s food intolerance is an elimination diet where the ingredients in a pet’s diet are slowly replaced, one by one. That means treats too! This is definitely a process, but one that will be well worth it for tail-wagging Fido in the end.

Another way to figure out what is causing your pet their discomfort is a food intolerance test. Once you find out what’s causing the food intolerance, you can quickly and safely remove it from their diet, and your pet can resume living their happiest, healthiest life once again!

Buy A Food Intolerance Test for Your Pet

Food intolerance can last for a lifetime, especially when your pet can’t explain to you how they’re feeling. You should talk to your veterinarian about any concerns you might have regarding food intolerances and the tips you can try to not expose your pet to such problems in the future. Now that you know what food intolerance in pets looks like, you can take the steps necessary to ensure your fur baby gets the treatment they need, and they’ll be on well on their way to healthier diet and a happier life! Because in the end, our fur babies’ happiness is what matters most!

Want to learn more about the intolerances that may be holding your pet back, causing them discomfort, and hindering their lifestyle?

Learn More About UCARI Pet Intolerance Testing Today!

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