Carbohydrates in dog food: Animal nutritionists promote their many benefits, yet various blogs seem to disparage them. You’ve heard the arguments before: Wolves didn't raid corn fields. "Carbs" aren't required, therefore, they don't provide value. The more protein, the better.

But instead of cruising on what we think we know about carbohydrates in dog food or sources of carbohydrates, let's dig into the science behind those claims, go beyond the grain vs. grain-free debate and investigate how carbohydrate really stacks up in the world of dog food nutrition…how carbohydrate works in your dog's body (or if it doesn't), why a protein-heavy diet might not be the way to go, and much more.


First Things First: What Is Carbohydrate?

Carbohydrate is one of the three macronutrients that provide the body energy and help it function (the other two energy-providing macronutrients are fat and protein). Under the umbrella of "carbohydrate" are three different kinds: starch, sugar and fiber. For dogs, starches and sugars are both digestible carbohydrate that provide a dog's body with energy it needs to run. Fiber can be soluble or insoluble; although fiber isn’t considered an energy source for dogs (more on that later), fiber plays a crucial role in helping your dog's digestive system run smoothly. So why are carbohydrates in dog food such a controversial topic?


Can Dogs Digest Carbohydrate in Dog Food?

Absolutely. Let’s take a look at the (very, very simplified) chemical structure of carbohydrate and understand how it works in the body before diving into some of the more hotly-debated questions. Starches and sugars are made out of bonded, hexagon-shaped simple sugar molecules (monosaccharides). A dog’s body can’t utilize the energy from carbohydrate until the monosaccharides have been separated. So how does that work?

Monosaccharide | Carbohydrate in Dog Food | Just Right by Purina


The enzymes that allow dogs to break down sugars and starches into usable parts are produced in the pancreas and small intestine. When sources of dietary carbohydrate for dogs like grains are consumed, the enzymes are released and begin breaking down starches and sugars into monosaccharides. Once the carbohydrate is “clipped” apart, a dog’s body absorbs glucose into the intestines, blood and liver, where they are then transformed into a readily available and efficient energy source. Since glucose is the primary energy source for living cells, being able to break them apart is crucial to provide a dog with the energy he needs.

Monosaccharide | Carbohydrate in Dog Food | Just Right by Purina


Now let’s talk about fiber. Fiber is a carbohydrate and consists of the same simple sugar building blocks as starches and sugars described above. But the difference is how the blocks are joined together. Dogs don’t produce the enzymes necessary to break the bonds in fiber, so they can’t convert fiber into a readily available energy source. Fiber does, however, benefit a dog’s body by keeping the digestive processes in working order in two ways:

  • Soluble/fermentable fiber, found in many whole grains, is the food for “good” gut bacteria  which, in turn, produce free-fatty acids to feed the dog’s colon cells and keep his digestive system healthy. 
  • Insoluble/nonfermentable fiber helps by absorbing water in the intestines and promoting gut motility (moving things down the digestive tract).

Long story short, dogs can digest carbohydrate in dog food, and they can digest it well. In fact, the carbohydrates found in corn, rice, barley and oats are nearly 100% digestible. We’re talking figures as high as 99.4% digestible for corn and 99.5% for rice! It’s compelling evidence – dogs don’t consume carbohydrate and digest it because they’re “forced” or “obligated” to, but because their bodies are elegantly designed to process carbohydrate and reap the benefits from it. When fed a complete and balanced diet, carbohydrate in dog food can help dogs not only survive, but thrive.


Wolves, Corn Fields & Your Dog

Whenever the topic of carbs in dog food comes up, someone will often point out that wolves, the ancestors of dogs, were carnivores and are never found raiding cornfields for carbohydrate; they only eat meat. It’s a common argument, but it’s only partially correct.

True, wolves and coyotes don't rummage around cornfields. But stomach content analysis has shown that they do consume fruits and vegetables, plus the stomach contents of their grass- and grain-eating prey that contains pre-digested carbohydrate. That means that they're still getting plant-based carbohydrate in their diet. Even carnivores are capable of deriving nutrition from multiple sources.

Diet of a Carnivore | Carbohydrate in Dog Food | Just Right by Purina "Farmers cultivating watermelons have experienced heavy losses from coyotes. Persimmons are frequently found in stomachs and, in areas where they are plentiful, comprise a significant part of the coyote’s diet." From Food Habits of Feral Carnivores: A Review of Stomach Content Analysis (1979) by S.M. Landry and H.J. van Kruinigen.


And, although it seems obvious to say, it’s worth pointing out – your dog is not a wolf. After generations and generations of domestication, the reasons why dogs are omnivores rather than carnivores are fairly distinct: 

  • Intestinal length: Carnivores have short digestive tracts because meat is fairly easy to digest. Herbivores have long tracts because plant matter is more difficult to digest. Omnivores, like dogs, have tract lengths that are somewhere in the middle, designed to handle both meat and plant material. 
  • Tooth structure: Dogs have the sharp incisors and canine teeth at the front of their jaws for ripping flesh. They also have flatter premolars and molars for grinding and pulverizing non-flesh.

 Canine Tooth Structure | Carbohydrate in Dog Food | Just Right by Purina


  • Enzyme production: As mentioned earlier, dogs produce amylase to help break down starches and sugars into monosaccharides (energy).

If a dog couldn't process carbohydrate, then his body wouldn't be built to process carbohydrate. While dogs love a good steak (who doesn’t?), carbohydrate in dog food is far from “bad” or even difficult for dogs to digest.


If It's Not a Nutritional Requirement, Why Use Carbohydrate in Dog Food?

Pet food manufacturers use carbohydrate as a key energy source in dog food because of its abundance and long shelf life – good things for the dog owner buying the food! And yet, dog food forums often criticize the use of carbohydrate and labels the ingredients fillers since carbohydrate isn’t nutritionally required. Why then? How can carbs in dog food help dogs thrive if it’s not a nutritional requirement?

The label “nutritional requirement” can seem deceiving yet pretty straightforward all in the same mouthful. A nutritional requirement (also called essential nutrition) is defined as functional or structural components that need to be consumed through food because the body can’t manufacture enough (or any) of it. An example in humans is the nutritional requirement for vitamin C – we can’t produce it ourselves and must get it from food in order to survive. Protein, fat, vitamins and minerals are structural components that dogs can’t make themselves. Even though carbohydrate isn’t technically a nutritional requirement, that doesn’t mean that it’s useless or can’t play a key role in helping your dog’s body function effectively.

The criticism that carbohydrate for dogs isn't necessary fails to mention the core reason for carbohydrates in dog food in the first place: its unparalleled nutritional efficiency. Let’s take a closer look.


Why Not Just Use Protein & Fat for Energy?

A dog’s body (and yours) can break down protein, fat and carbohydrate for energy. But what’s the difference between getting energy from carbohydrate versus the other sources? Carbohydrate is relatively simple and direct to break down and extract energy. When there’s no carbohydrate left, only then does the body turn to breaking down the other nutrients.

When your dog’s body processes protein for energy, it must first break it down into small chains of proteins called peptides, then break it down into amino acids, then use even more energy to break those amino acids into glucose (a process called gluconeogenesis) for energy the body can use. It’s a longer, more effort-intensive process, but turning protein into energy can be done.

Look at it this way: Protein, fat, vitamins and minerals are all structural components – they’re like the parts and pieces needed to build a car. Carbohydrate is simply the fuel – its job is to keep the car running. It’s true that dogs can survive on protein and fat as energy sources, just like you can make a car go on cooking oil. But why not use the most efficient form of energy? Why not just fill the car up with gasoline? Starch digestion is just the fastest way to get energy, while getting glucose from protein and fat is like adding a middle man to the process.

Though many dog owners love the idea of feeding their dog a diet higher in protein – real meat! – at the end of the day, protein has its place in providing amino acids to build your dog’s body. Carbohydrate is the most effective method to make that body go by providing energy better and more efficiently than protein ever could.


Feeding a Complete & Balanced Diet

We all want to believe deep, deep down, our dogs still maintain the essence of wolf ancestors as cunning, carnivorous, majestic hunting machines. But at the end of the day, the science just doesn’t support that idea. Domestic dogs are omnivores and – (really, it’s ok!) – they can and should be fed as such, with carbohydrate in dog food doing its part in helping your dog live a long, happy, healthy life.


Just Right by Purina offers personalized, natural, complete and balanced dog food – tailored for your dog's nutritional needs – with your choice of a grain or grain-free blend.