Are Grains Bad For Dogs? – What Does Science Say

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grains and rice

Perhaps you think that grain is a cheap ingredient in dog food. Something utterly unimportant compared to meat and protein. Or even harmful.

And who could blame you? With all the bad rap that gluten and grains have received in the last few years, a grain-free diet seems the right way to go.

It’s hard to make sense of different health claims — we simply want the best for our family members, four-legged or human.

How bad is grain for your dog, really? Let’s see.

You might be surprised once we separate the proverbial wheat from the chaff.

Key Information

Grains are not bad for dogs

Dogs are omnivores and can digest grains well. Grains provide carbs, fiber, vitamins, minerals, and antioxidants for dogs.

Grain allergies are rare

Most dogs are not allergic to gluten or grains. Meat and dairy are more common allergens. Grain-free diets are not necessary for most dogs.

Whole and ancient grains are better

Whole grains and ancient grains have more nutrients and less chemicals than refined grains. Examples are oats, barley, buckwheat, amaranth, and quinoa.

Grain-inclusive dog food quality varies

Not all grain-inclusive dog foods are equal. Check the ingredient list, nutritional profile, digestibility, gelatinization, and production standards when choosing a dog food with grains.

What Are Grains?

Most grains are seeds of grass. They can be categorized in several ways.

There are also pseudo-grains. These don’t come from grass but rather a bush. Examples of pseudo-grains are buckwheat, quinoa, amaranth, millet, and teff.

Gluten VS Gluten-Free Grain

Gluten is a type of protein.

Some grains contain gluten. These include wheat, spelt, rye, and barley.

Did you know that there are also gluten-free grains? Oats, rice, and corn do not contain gluten.

You should still check your box of oats for a clear “no gluten” statement. Sometimes, other production ingredients, like wheat or soy, might seep in.

Industrial VS Ancient Grain

All the grains are ancient in the sense that they have been around for thousands of years.

But the industrial grains — like wheat, corn, and rice — have been modified and bred more than others. The idea is to make them resistant to pests and increase the yield.

This has drawbacks since such grains are less nutritious.

The ancient grains, on the other hand, haven’t changed much. Grains like amaranth, quinoa, buckwheat, sorghum, and millet are more nutritious than industrial ones.

They are also less likely to contain herbicides. If they remain in the food, they can cause issues down the line.

Whole VS Refined Grain

Grains are usually sold in two forms: whole and refined.

Refined grains, like wheat or white rice, have been milled to remove their husk, bran, and germ layer.

This makes them more shelf-stable since they retain less moisture.

However, the process also removes most of their minerals, vitamins, and fiber. A refined grain is usually lower in fiber and higher in carbohydrates.

It is less nutritious than a whole grain that has been minimally processed to remove only the germ.

Whole grain has a lot of essential minerals, vitamins, and fiber intact.

For instance, white rice is less nutritious than brown rice. But white rice is easier to digest, and brown rice is also more expensive.

oat and wheat grains

Can Dogs Eat Grains?

Yes, dogs can eat grains. Dogs are omnivores.

But why do dog owners still question this statement? We know that dogs descended from wolves, and, well — it’s unlikely you ever saw a wolf eating a pretzel.

Here’s the thing — dogs did come from wolves, but they’ve also been by our side for a long time.

Meaning, over time, they adapted to human food. In fact, dogs have amylase in their pancreas. The role of amylase is to dissolve starch and carbs.

The study by Swedish scientist Erik Axelsson proved that amylase is up to 28 times more active in dogs than wolves. So, dogs can digest grain much better than their ancestors.

It’s true that certain dog breeds are more prone to gluten sensitivity and allergies. Irish setter, for example, is one of those. But that doesn’t mean all dogs are carnivores.

Are Grains Good for Dogs?

Grains are a rich source of carbs — which produce energy. Good carbs are especially important for puppies and active dogs, since they support growth, development, and provide energy for everyday activities.

But grains provide a lot more benefits apart from their energy-boosting abilities.

Grains contain fiber, antioxidants, and minerals. Dietary fiber is crucial for proper digestion, weight management, and heart health. Foods rich in fiber take longer to digest, so there are no blood sugar spikes, and the energy is more stable throughout the day.

A wholesome grain is especially rich in B-vitamins, which are vital for cognitive function, nerves, and muscles. They also support a healthy coat, nourish skin, and promote the immune system in dogs.

The antioxidants in grains protect dogs’ cells from oxidative stress. Meaning, they guard against cell damage — which further strengthens the immune system.

Whole grains and ancient grains are especially rich in all of the above nutrients. When looking for dog food, you want these on the ingredient list. They will provide your canine with most benefits.

Speaking of dog food, grains are significant since they bring the kibble together. They also give it its proper shape and texture.

Finally, grains are cheaper than meat — meaning, they enable dog food kibbles and mass production. 

The best part? If the dog food recipe is good and well-balanced, your dog will get complete nutrition at a fraction of the cost. The key being a well-balanced diet (we don’t want our dogs to starve).

When Are Grains Bad for Dogs?

So should we feed grain to our furry friends with no discernment?

Not really. In fact, there are several instances when grains can be harmful, if not downright dangerous.

Gluten and Wheat Allergies

Some dogs are allergic or sensitive to gluten and wheat. For these dogs, ingesting gluten might trigger an allergic reaction, anaphylactic shock, and many health issues.

Before you diagnose your canine with celiac disease or gluten sensitivity, you should know that grain allergy is not as common as marketers would like us to think.

Actually, the most common food allergies in dogs are to meats. Beef and chicken are in the top three allergies.

After that, the most common allergy is to dairy, and only then, to gluten.

If you suspect that your canine is allergic or sensitive to gluten and grains, ask for veterinary advice.

Glycemic Index & Diabetes

The glycemic index is a tool for human nutrition. It measures how fast a certain food raises blood glucose levels in humans.

As such, it does not apply to dogs. There are no FDA-established values of glycemic index for canines.

Still, some dog breeds are more prone to diabetes than others — and many of them include smaller breeds like Pugs and Miniature Schnauzers. In case of diabetes, it’s important to control a dog’s carb intake.

As for the glycemic index, you should know that the GI of a single ingredient doesn’t say much in the context of the kibble. Cooking changes the glycemic index, and you should look at the GI of the whole formula.

Still, a much better and safer approach is to read the guaranteed analysis and check calories and sugar content. Furthermore, dog foods for diabetic dogs are modeled after human diets.

Digestive Issues

Gluten allergies are not very common. But digestive issues, on the other hand, are much more widespread.

Grains are rich in fiber that can provide additional health benefits to both humans and dogs alike. Fiber is proven to regulate digestion by stimulating the growth of healthy bacteria in the digestive system.

However, it can also cause digestive problems. Grains like corn, wheat, or rice may lead to flatulence, bloating, stomach discomfort, and other digestive problems.

In these cases, grain-free dog food might help.

Weight Management

Any food high in calories can lead to weight gain. This does not refer only to grains.

Grain-free diets can also cause weight gain in dogs. Just because they don’t contain grains, doesn’t mean they are free of carbs.

In terms of weight gain, make sure you check the calorie content on the label and feed your dog accordingly. The calories don’t depend solely on grains, but they are crucial for weight management.


Wheat and corn are the top two crops that are likely to be genetically modified.

They are also among crops that can contain glyphosate — a controversial herbicide said to cause infertility and cancer in humans.

Grains like corn and wheat may very well be contaminated with glyphosate. This is concerning since we do not yet know all the consequences of glyphosate on human health.

How Many Nutrients Does a Dog Get From Grains?

There is no doubt that grains are nutritious. Studies have shown they contain varying degrees of protein, fiber, fat, vitamins, and minerals.

All these can be great additions to your dog’s diet.

But do dogs get all those nutrients? Two factors influence how much of the good stuff a dog can metabolize.


Most dogs can digest animal protein more efficiently than plant material. Animal sources contain a full amino acid profile that your dog needs.

However, that doesn’t mean plants aren’t a good protein source. But it takes several sources for a full nutritional value.

We also know that excess fiber can slow down digestibility in meat-eaters. High–fiber content will impact it significantly.

What do all these mean? When you are looking at the ingredients list, hopefully, there will be several different plant sources.

If the plant protein is dominant in dog food, make sure there isn’t too much fiber — otherwise, your dog might not be able to use most of it.


Gelatinization is the heating and cooking of the kibble ingredients, specifically starches. The starch is heated at an appropriate high temperature until it swells, loses its original crystal structure, and becomes soluble.

Starch gelatinization has been linked to digestibility. For example, rice becomes more digestible once it’s been gelatinized. It also loses some of the nutrients.

However, some grains, like corn, retain their (non-)digestibility even after gelatinization.

In other words, they are viewed as cheap ingredients — since dogs can’t digest their nutrients as efficiently.

What do these mean for you and your dog?

Sometimes a food is just not as digestible — i.e. its nutrients can’t be absorbed properly.

A recent study may have found a solution to this.

The corn is usually ground before gelatinization. The study mentioned that grinding corn into even finer particles may improve its digestibility. Meaning, the dogs can digest more of corn afterward.


Is Grain-Free Dog Food Better?

All this grain talk maybe got you thinking about whether you should just choose a grain-free diet.

Grain-free dog food has been very popular in the last couple of years. Its proponents claim their dogs’ skin improved, the coat got shinier, and they are thriving.

This is quite possible if the dog is allergic to grain. A grain-free diet usually contains sweet potatoes and pea protein to address grain allergies.

In some cases, grain-free food will help with joint health, immune function, and healthy gut lining.

But sometimes, it’s about the change of diet itself and not the exclusion of grain. Maybe, by choosing a grain-free dog food, you have inadvertently removed another allergen, like chicken or beef.

Don’t think that grain-free dog foods are a panacea. They are not.

In fact, in 2019, FDA suspected that grain-free diets are the main reason behind dilated cardiomyopathy in dogs. DCM is a severe heart disease caused by a lack of taurine.

Hundreds of dogs got sick, and more than 90% of them were on grain-free dog food.

For some dogs, the condition improved once they switched to grain-inclusive diets again.

So, a grain-free diet may be useful in some cases — but in others, it is potentially fatal.

Before you opt for grain-free food, talk to your veterinarian about food sensitivities in pets, DCM, and other risks involved.

Which Grain Is Best for Dogs?

Let’s say your dog doesn’t have a grain allergy, and there is no reason to put them on grain-free pet food.

Are there some healthy grains to look out for?

Why, yes. Glad you asked.

Whole Grain

Most veterinarians and pet experts agree that whole grain is good for your dog.

The reason is that its nutrients are intact — which means they offer much more than mere energy, i.e. carbs.

Whole grain is a tiny powerhouse of vitamins, minerals, fiber, and carbs.

Whole wheat, brown rice, barley, buckwheat, and whole oats are wonderful additions to your dog’s diet.

Ancient Grain

Ancient grain has not been altered or processed much.

This means two things:

  • More nutrients — they are especially rich in vitamin B, zinc, and fiber
  • Less tampering — ancient grain hasn’t been genetically modified like industrial ones, and generally contains less pesticides, so it’s safer

Grains like amaranth, millet, kamut, and sorghum are worth looking further into.

wheat middlings

Which Grain to Limit or Avoid

Some grains should be limited in dog food.

A caveat: these grains are not bad per se, as some would have you believe. They are simply lower in nutritional value.

That doesn’t mean they should never be used. Sometimes, these are added to complete the nutritional profile of a recipe.

We just think that, ideally, they shouldn’t be higher up on the ingredient list.

Refined Grain

Grains like wheat or white rice have been stripped of their nutrients.

During the production, a hull is removed from the grain. This does two things: prolongs shelf-life and makes it highly digestible.

It also removes vitamins, minerals, and fiber. What’s left? Mainly starch.

Refined grains can be used to boost the calories and sugar content in a recipe. They should not, however, be primary carbs in a recipe.


You may have come across some interesting names in a dry dog food recipe:

  • Corn gluten meal
  • Wheat middlings
  • Wheat gluten
  • Oat fiber

These are all by-products of food production.

A common myth circulating the web is that by-products are nothing but cheap fillers.

Not true — for example, wheat middlings is known to be a great source of protein and fiber.

It’s very easy to discard an ingredient. All these have their place in the context of a recipe.

They are, however, less nutritious than the original grain — and as such, shouldn’t be the main carb source. But they can still be used to complement the whole grain in the recipe and raise the nutritional value.

How to Ensure Grain Quality

Is all grain-inclusive dog food created equal? Of course not.

The question of grain is also about the formulas and pet food industry on the whole.

When deciding on grain-inclusive food, there are several things you need to take into account.

Nutritional Profile and Ingredients List

The ingredient list tells you what grain is used — and it does have some valuable info.

The position on the list shows the amount of an ingredient in a recipe. Ideally, a whole or ancient grain should be higher, and refined grain and by-products further down the list.

Other than that, there is little you can conclude from the list alone. Remember — digestibility and gelatinization will affect the ingredients in the whole recipe. It’s hard to get correct info on these two.

That is why the nutritional profile of the formula is much more important.

Make sure the profile follows the AAFCO guidelines and the life stage or specific needs of your dog. For example, large-breed dogs will have different needs than smaller breeds.

Feeding Trials

Some pet food manufacturers conduct feeding trials on their dog foods.

These are designed to test whether the dog food formula does what it’s supposed to. Meaning, if the nutritional profile covers a dog’s dietary needs.

If a company has done the trials, the bag will read:

“Animal feeding tests using AAFCO procedures substantiate that (name of product) provides complete and balanced nutrition for (specific life stage).”

Dog owners can also contact the pet food manufacturer and ask about the trials.

Company Research & Quality Assurance

There are several other things that you can check to make sure you’re buying from a credible pet food producer.

First off, does the company publish research papers? Ideally, they would have a nutritionist on the team and publish in peer-reviewed journals.

Secondly — and this extends beyond the pet food — are their production facilities complaint to food production standards?

FDA and AAFCO (Association of American Feed Control Officials) regulations, along with ISO and HACCP standards, ensure high-quality production. They also address some of the prevailing concerns — like mites and mold.

Our Verdict

Grain is not the villain. The best food is the one that helps your dog thrive.

Pet owners have been hearing a lot about gluten and grains lately. Most of these claims are grossly overstated, and they do nothing but instill fear and promote grain-free dog foods.

Don’t buy into the hype. Grain-free diets may replace grains, but they come with their own set of challenges. Every dog has individual needs.

As usual, proper information is the key to choosing the best dog food. With quality research and veterinarian consultations, your pets will be happy, healthy furballs.

Want to learn more? Check out our takes on best grain-free dog food and best dog food with grains.

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Kim Studdard is a freelance writer for many websites in the pet universe. When she isn't spending time with her family and pets, or saying "Look a dog" everytime she sees one, you'll find her reading a book or traveling the U.S.

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