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Nutrition Nuggets is the newest offshoot of petMD's Dog Nutrition Center. Each week Dr. Coates will use her expertise and wisdom to blog about the intricacies of dog nutrition.

Is Grain-Free Really Better for Dogs?

November 21, 2014 / (4) comments

Doesn’t it seem like “grain-free” dog diets are taking over the pet food aisle? I’m surprised at just how omnipresent they’ve become. While there is nothing inherently bad about grain-free dog food, I worry that owners are being led to believe that grain-free foods are necessary for dogs. This is simply not the case.


Let me first say that there are times when a particular individual will benefit from a grain-free diet. For example, a dog who is allergic to wheat should obviously not be fed a food containing that type of grain. The question I want to look at, however, is, “Are there any benefits from going grain free for healthy dogs?” I believe the answer is “no” and that the popularity of grain-free diets is based on a couple of basic misunderstandings.


First of all, “grain free” is not the same as “carbohydrate free.” Starch, a type of carbohydrate, is essential to the formation of dog food kibble. Therefore, if you are feeding dry dog food, it has to contain a certain amount of carbohydrates. A quick look at the ingredient list will reveal the presence of potato, sweet potato, tapioca, or other carbohydrate sources. The phrase “grain-free” is not a substitute for “carbohydrate-free” or even “high-protein,” which is what most owners who buy these products seem to be looking for.


Contrary to what you might have heard, dogs do have all the digestive enzymes needed to break down, absorb, and utilize nutrients from grains. I’ve heard proponents of grain-free diets argue that dog saliva does not contain the enzyme amylase, which is needed to break down carbohydrates from grains. While it is true that dogs don’t make salivary amylase, their pancreas does make the enzyme, and since dogs tend to swallow large chunks of food without chewing, the need for salivary amylase is questionable. The lining of the dog’s small intestine also produces brush border enzymes that are responsible for much of the carbohydrate digestion.


Don’t get me wrong. Even though dogs digest carbohydrates quite well and grains are a healthy source of carbohydrates for most dogs, pet food manufacturer can overdo it. Carbohydrates are cheaper than animal-based sources of protein, so the financial lure of maximizing the former while minimizing the latter is hard for some companies to resist. If what you’re looking for is a low-carb, high protein dog food, you need to be looking at the guaranteed analysis on the back of the bag rather than the marketing hype on the front.


A food’s carbohydrate percentage does not have to be included in the guaranteed analysis, but it’s quite easy to estimate. Add up the percentages for crude protein, crude fat, crude fiber, moisture, and ash and subtract the result from 100%. The result is a ballpark figure for the food’s carbohydrate percentage. If a number for ash is not provided, use 6% as an estimate for dry food and 3% for canned.


If you want to compare dry and canned foods, you’ll probably need to do a bit more math because most companies report their guaranteed analysis on an as fed rather than dry matter basis.


  1. Find the percent moisture and subtract that number from 100. This is the percent dry matter for the food.
  2. Divide your carbohydrate percentage by the percent dry matter and multiply by 100.
  3. The resulting number is the carbohydrate percentage on a dry matter basis.


Analyzing a food’s guaranteed analysis is not as simple as buying into the buzz around grain-free, but the work will let you make an informed decision about what to feed your dog.


Dr. Jennifer Coates



Image: Jaromir Chalabala / Shutterstock


Comments  4

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  • Substitutions
    11/21/2014 09:51pm

    I"m thinking that maybe "grain free" might be something like the human "Sugar free" because I believe that to keep the taste pleasurable, the amount of fat is increased in "Sugar free" items.

  • Carbohydrate Analysis
    11/22/2014 02:27pm

    What is the ideal carbohydrate percentage that we should be looking for during the analysis? I would love to know the percentages for a moderately active mature adult, an active adult, and a highly active/working adult dog. Also, are there different carbohydrate goals in males vs. females? I'm not 100% sure if ideal body fat percentages and resting metabolism differ in females vs. males like it does in humans. Thank you in advance for further clarification!

  • 11/24/2014 07:55pm

    Dogs don't have a specific need for carbohydrates so it's difficult to recommend a particular number to look for. The information that comes closest to what you are looking for is found in the National Research Council's recommended allowances for dogs. Take a look at this post:


  • well
    06/27/2016 12:09pm

    A Allergie with food is serious, my dog can not have grains, white potatoes and sugar beet, he does not eat sugar himself and if there is sweet stuff in it he wont eat it.

    Symptoms, Bloated, sluggishness, rash and extremely dirty eyes, take these food stuffs away, no problems a healthy fit dog

    Therefore to call the food balanced and correct and that more than likely its the owner that thinks that the dog is allergic is rubbish.

    I started making my own biscuits, from organic rice flour, buckwheat and Spelt all gluten free no sugars, dehydrated meats cheese with no lactose never add salt dehydrated veggies, while at first the dogs that have been on high sugar content biscuit pulled there nose up and would not eat them after persisting they now do not take the "bad" biscuits. and a lot of the dogs stopped having hyperactivity, and dirty eyes.

    I now have dry food for my dog no grain, no white potatoes and sugar beet pulp he is doing really well as the food is high in meat content and he does get chicken (free range) and beef (free range) as well it is very economical, as with he additive rich foods he seemed to be hungry all the time and had no rest hyperactivity was another symptom.

    I therefore would urge dog owners to read the labels of the food they buy there dogs if they suspect there is a problem, while it may not be grains potatoes (white) especially the skins can have terrible reactions, often if it is grain free they replace the grains with white potatoes, sweet potatoes are good.

    If your dog has dirty eyes constantly, and you cant explain why more that likely its the food your given him/her. Vets will sell you breed specific foods (very expensive), don't fall for that research on line and really good healthy foods do not have to be a horrible price either and somemay be expensive but the quantities that you feed are less and will still work out cheaper, fresh veg raw or cooked you maybe surprised what your dog likes. feed organic if you can afford it with veggies as there are no nasty prays used on them. My dog loves his sugar snaps (raw)(also called snow peas I think or pop peas) he loves broccoli raw and cooked, and butternut squash (raw and cooked) hates carrots with a passion so a bit of fresh veg and some chicken or other meats in moderation keeps the meal interesting with his grain free potatoe and sugar beet free kibble I have a healthy happy Vizsla with no dirty eyes.

    (soon as he eats bread white or brown, potatoe (which happens sometimes in weekends as a treat) he has runny dirty eyes the next day for two days) I rest my case it is tried and tested.