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Genetics Markers Prove Dogs Have Evolved to Digest Carbohydrates and Starches

One could spend all day, or more, engaging in (sometimes heated) dialogue about what our pets should eat. Depending on your personal beliefs, education, and experience, your perspective could be vastly different from another pet owner. Even within the veterinary community, there are a wide range of recommendations as to what is the most appropriate style of feeding for our companion canines and felines.

Should your pet eat a whole-food based diet made up of nutrients identical or similar to the form created by nature, or a highly processed diet engineered into a dehydrated (and seemingly devitalized) piece of kibble?

What about the components that make up a particular diet? Should pet food have whole meats, vegetables, fruits, and grains? Or is it sufficient to feed protein and grain meals and by-products that have been coated with rendered fat and infused with artificial colors to increase palatability and appeal to owner aesthetics (respectively)?

Should you be feeding grains and starches to your pooch? Can dogs even digest them? Recently, a study published in Nature magazine proved that dogs’ domestication complements environmental and geographical changes associated with their role as companions to humans. It’s proven in their genes, which have evolved similarly to man’s and reflect dogs’ ability to digest grains and starches.

The authors of the study, titled The Genomic Signature of Dog Domestication Reveals Adaptation to a Starch-Rich Diet, conducted "whole-genome resequencing of dogs and wolves to identify 3.8 million genetic variants used to identify 36 genomic regions that probably represent targets for selection during dog domestication. Nineteen of these regions contain genes important in brain function, eight of which belong to nervous system development pathways and potentially underlie behavioral changes central to dog domestication.

“Ten genes with key roles in starch digestion and fat metabolism also show signals of selection. We identify candidate mutations in key genes and provide functional support for an increased starch digestion in dogs relative to wolves. Our results indicate that novel adaptations allowing the early ancestors of modern dogs to thrive on a diet rich in starch, relative to the carnivorous diet of wolves, constituted a crucial step in the early domestication of dogs."

As domesticated dogs are believed to have evolved from wolves nearly 11,000 years ago, their evolutionary process parallels a similar genetic shift seen in humans. Today’s dogs and humans eat and can digest a wider variety of foods in comparison to the primarily meat protein meals that were hunted, killed, or scavenged by their lupine and Cro-Magnon predecessors.

To fit modern times, we should be providing our canine companions some variety in their diets. I am an advocate of both dogs and cats eating whole food meals instead of processed diets. As ChooseMyPlate.gov does not advocate that we humans regularly eat highly processed foods, the same basic principles should apply to our canine and feline companions.

Even though today’s dogs can digest grains and starches, I don’t recommend that such nutrients form the majority of a dog’s diet. Any grains or starches made to be consumed by our pets should be whole-food based, cooked, and included in a small to moderate quantity (30% or less of the volume of a particular meal), complementing the larger percentage of meat, vegetable, and fruit ingredients.

Although commercially available and home prepared diets that are 100 percent free of grains and starches are popular, there are nutritional benefits stemming from their inclusion. Whole grains like brown rice, barley, etc., are good sources of minerals (Selenium, Manganese, etc.) and can even serve as substrates (pre-biotics) on which beneficial bacteria (pro-biotics) grow. Starches like russet and sweet potatoes, banana, etc., are rich in vitamins (A, B6, E, etc.) and minerals (Potassium, Manganese, etc.).

Part of where my concern about pets eating commercially available pet foods containing grains and starches lies in the quality of the ingredients. The majority of canine and feline diets are made with ingredients that are "feed-grade," which are of lower quality than "human-grade" and have higher potential to contain unhealthy substances (e.g., deoxynivalenol [vomitoxin], aflatoxin, etc.) according to the FDA Regulatory Guidance for Toxins and Contaminants.

Short or long term consumption of these toxins can cause inflammatory bowel disease, kidney and liver damage, or even cancer (see petMD article: Are You Poisoning Your Companion Animal by Feeding 'Feed-Grade' Foods?).

How you feed your pet is your personal choice. Nobody can force you to feed a particular commercially available or home prepared option. My best suggestion is to model your pet’s diet after that which humans are recommended to eat, which means choosing a variety of whole foods and minimizing processed foods.

What’s your perspective on how our companion canines (and felines) should eat?

Dr. Patrick Mahaney

Image: Chopstick Joe - Joe eating rice by Nicole Hanusek / via Flickr

Comments  19

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  • Your article
    01/29/2013 05:19am

    Thank you Doctor for great article on dog feeding. I have carefully read what you wrote, and amazingly is the kind of diet I always provide my two dogs (Astor & Callas) with. It was a very helpful one, indeed!. greatings of a daily reader, from Argentina. Martin.

  • 02/06/2013 01:06am

    Thank you for your comments. Greetings from California! It's great to learn that we have PetMD readers in Argentina (a place I've always wanted to go).
    From my clinical experience, I've recognized the importance of feeding whole food based diets to our pets instead of processed food; especially considering the mild to severe and potentially irreversible diseases (obesity, diabetes, cancer, etc.) that are occurring in increased frequency as a result of consumption of processed foods made with feed-grade ingredients.
    I hope to see you back again on my PetMD page.
    Dr. PM
    www.PatrickMahaney.com

  • Dogs have evolved ... .
    01/29/2013 05:38am

    first of all, I'd love to know who paid for this 'study'... and Secondly, I will continue to provide my dogs, and my family as 'species appropriate' diet as I can afford. And for the dogs, that does not include potatoes or pasta - other than perhaps as a 'treat'. Only in very recent years have potatos, rye, tapioca, peanut hulls, and other , IMPO, waste products been included in pet foods as supposed 'nutritional' benefit. Raw ( for my animal ) meats, eggs, bones, fresh green leafy vegetables, some fruit will continue to make up the mainstay of their daily diets. They do not get a 'grain' or 'carb' free diet, but what I do add is in appropriate quantities, 'pre-digested' (steamed/cooked/mashed) and not as the 'base' of their diets.

  • 02/06/2013 01:07am

    Thank you for your comments.
    It's great to hear that you are providing your pet with dietary variety and whole foods.
    Dr. PM

  • It "proves" nothing
    01/29/2013 09:01am

    The article proves nothing. It is some evidence in one direction, while there remains a lot more evidence in the opposite direction. If dogs have "evolved" away from meat, then why do other studies show that feral dogs prefer killing and eating small animals over nibbling on foliage? And, why do other studies show that wolves will also eat fruits, grains, and greens?

  • 02/06/2013 01:10am

    To say that my article or the Nature-published study "proves nothing" is a gross understatement. The well-thought out study indicates that dogs are capable of digesting a variety of foods, which is the manner by which we should feed them (real food, minimally processed, etc.) even if it is less convenient or costs more to do so.
    Dr. PM

  • 02/06/2013 01:34am

    So very true, Dr Mahaney. Just take a dog for a walk in an area where crows may have dropped chicken bones out of garbage cans, as an example. Dogs are scavengers and will eat pretty well anything. They are lucky we are around to keep their diet nutritious and save them from brittle bones at times, just for starters.

  • 02/06/2013 07:14am

    Doctor, you apparently do not know the difference between "proof" and "evidence". The article's evidence is contradicted by evidence in other articles, and therefore it's contention is not proved, at all. And because of those contradictions of evidence, the article's conclusion overreaches the limits of its own evidence.

  • Derisive comments above
    01/29/2013 02:42pm

    While the detractors of science who prefer to put their faith in the 'dog'ma that has no data to back it, they can easily find the source of funding for the study being discussed if they pay the fee to purchase it at http://www.nature.com/nature/journal/vaop/ncurrent/full/nature11837.html. All they need to do is click on the "Affiliations" tab at the website, but maybe the question of funding has come about because the writers aren't trained to read good research abstracts?

    All living things are continuously evolving genetically and those who don't understand this clearly are lacking in education, as well as observational skills.

    As Dr Mahaney points out, both nutrient variety and good quality ingredients are important. In particular the mention of whole grain rice means a supply the best form of substrate for the gut to get the most out of what is eaten. The study proving gut flora information also mentions beet pulp which is often found in commercial pet foods. Since reading the data attached to the 1999 Buddington study I have had no qualms when it comes to the feeding SOME good quality plant sources of nutrients, both for cats and dogs as that data also proves an acceptance of plant materials, (http://www.ncbi.nlm.nih.gov/pubmed/10188819).

    Dogs have not "evolved away from meat", they just manage to live MUCH longer on a more varied supply of nutrients these days. Much of what our pets see as food in today's world depends upon what they were taught as pups to eat by the adults, and/or owners.

    Personally I would never take in a dog that needed to eat raw meat as I wouldn't want the children in my home to be handling the pets, and I wouldn't want to have to deal with the shorten life span coming from a high cholesterol diet.

  • 01/29/2013 07:34pm

    As usual, westie, when you have nothing of value to offer, you attack the messengers and deny their evidence. Denial & attack, denial & attack. Your M.O. is like a tattoo on your forehead.

  • 02/06/2013 01:13am

    Thank you for your insightful comments and willingness to do extra research in including hyperlinks to information that backs up your statements.
    Your clear thinking and reasonable approach to the (obviously) controversial topic of what pets should/not eat provides a nice contrast to other comments on this article.
    Dr. PM

  • Why is food so emotional?
    01/29/2013 02:55pm

    I do not understand why food has become such a horribly emotional subject. I have always been quite fit; I (and my sheltie!) exercise every day. I try to eat well and feed him well but I also have very healthy friends with healthy dogs, that do not do just as I do.

    For me, I stick to low-fat, partial vegetarian (I do eat fish) and mostly whole grains. I do eat some sweets, in small, planned-for portions. My favorite lunch is a whole-wheat english muffin with peanut butter and an apple. My dog is always happy to have a taste of both. :-) Breakfast may be raisin toast and an ounce of lowfat cheese and I make home-cooked meals for myself and my husband. I always use whole grain pasta and mostly whole grain bread or tortillas for myself. I generally have to provide my husband with a different bread and forget brown rice for him!

    My doggie gets small portions at his meals. He gets chicken, turkey or fish (I do cook it for him...feels safer to me) pumpkin or sweet potato, yogurt and frozen green beans. I give him a half-teaspoon of salmon oil 3 or 4 times a week. I use a high-quality kibble for training treats...right now he favors salmon and garbanzo bean from Artemis OSOPURE. I also bake him doggie cookies, usually peanut butter or pumpkin, for a special reward. He also enjoys sharing whatever I have. :-)

    I am 51, still a size 4 or 6. I am very strong in the gym and can out-hike most young people. My sheltie is also a good, little hiker. To be honest, I believe that exercise is the real key to good health. You can eat a perfect diet and still be weak and flabby. Even if you are not always perfect in your eating habits, exercise will make you stronger and healthier.

    I have many friends who feed raw diets to their dogs. I dog-sit for people who feed raw. The dogs are healthy. Most people who feed kibble-based diets that I know add some extra goodies and their dogs are also healthy.

    The vet here has suggested a good way to feed. I did not think she was insisting anyone do what she said...it was a suggestion. I feed my sheltie much the way she describes and he is very fit and healthy. That does not mean there are not other ways to do it.

    It is the same for people. There are many healthy ways to eat. The most important thing though, is get away from the computer and go get some exercise.

  • 02/06/2013 01:16am

    Thank you for your comments.
    I appreciate hearing how you take care of yourself through a healthful/whole food diet and exercise, then apply similar principles to your dog. Those of us living a lifestyle which focuses first on health through good habits understand the value of real-food based nutrients that are minimally processed as a means of providing nutrition that processed food cannot energetically equal.
    I hope you and your pet have many years of good health ahead of you!
    I hope to see you back again on my PetMD Daily Vet page.
    Dr. PM
    www.PatrickMahaney.com

  • Quality
    01/29/2013 06:17pm

    "lies in the quality of the ingredients"

    In my opinion, that's true for starches as well as animal-based protein. We've all heard the urban story about the people that were sitting in a popular fast-food restaurant and noticed a meat delivery with the boxes labeled, "Fit For Human Consumption."

    If there's any truth to the story at all, I'm not sure I'd be eating there again any time soon.

  • 02/06/2013 01:18am

    YES!
    Great story. I hope it's not just an urban myth.
    I'd love to see a photo of the "fit for human consumption" sign. Perhaps you know someone who frequents fast food restaurants that can snap a shot!
    Thank you for your comments.
    Dr. PM

  • 02/06/2013 03:58am

    As expected, this is an urban story. Snopes.Com:

    http://www.snopes.com/food/prepare/badmeat.asp

  • 02/06/2013 04:00am

    Please note that the whole URL did not post. If anyone uses it, please add ".asp" at the end.

  • Pay now or pay later!
    01/02/2014 07:28pm



    Thanks Dr. Mahaney for this informative article about this study that was done and states that dogs can now digest carbs and starches. Knowing that species appropriate diet is mostly meat for dogs, I would have some concerns about about who authored this study and can we trust what has been written. I would feel more comfortable knowing if this study was not funded by any of the dog food manufacturers.

    As I walk down the aisles of pet food stores and enter online dog food sellers stores, I see product after product that has so much bad stuff in it, grains are right on the top of my bad list. I fear the people who buy this kind of food for the dogs is setting them up for a shorter life and more illness. I see so many low quality ingredients that are used by these pet food manufacturers all in the name of profit. Yet when you read the front of the package, you would think this is the best food for any dog, yet all it is doing is shortening their lives. I have to wonder how many pet owners don't know what they are really feeding their pets when they by grain based foods.

    On a cat online support group I belong to, the moderator says you can pay more now and provide your cat (or dog) with a good health species appropriate diet comprised of mostly all meats, OR, you can spend less now, buying grain based foods and pay much more at the end of your pets shorter lives in vet bills for an animal that was brought up on poor quality food.. That was a no-brainer for us.

    Based on her thinking, when we (wife and I) adopted our first Doberman Red, we got her from a Doberman rescue group here in Florida that is run by our friends, they told us Roxie had a tough first 4 years of life and I immediately felt a poorer diet also was given to her.. We were told Dobies live to about 7- 9 years at the longest.. We decided to feed her a good quality kibble, she was given Taste of the Wild High Prarie, it has NO grains and four kinds of meats, and mixed in other Taste of the Wild kibble blends short term just for a change.

    Roxie left this world at 14 years of age and we definitely attribute this to her quality diet covered with mounds of love.. Considering her start in life was not the best, the good diet she ate for much of her life gave her longevity and she seldom was at the vets office during her life.

    My seven cats also get a NO grain diet of EVO canned food and they are all very healthy, extremely healthy, they were given this food since adopted as babies. The oldest is now 15 years.

    I honestly believe that even if dogs can now digest carbs and starches, this still means they are not getting enough meats in their diets and I would fear a shorter life for them, grains are cheap and plentiful in many dog foods. If on the other hand these grains can not be truly digested, then they most likely will cause more illness at a younger age.

    Our pet food bill monthly comes to about $300. There are plenty of other things we could use that money for, but we would never consider a lower quality diet. All of our guys are very healthy, Oso, our newly adopted Dobie Red at 1 1/2 years old who remains on the same diet we fed to Roxie. So we are willing to pay more for a good quality species appropriate diet (meats, no grains) now and provide them with a good and healthy life. Pay now or pay later!

    We are what we eat, and we feel strongly this also pertains to our pets we are entrusted with in life.. We could not imagine sitting down to a nice healthy meal while our pets ate an inferior diet that include grains and often no meats.. No grains, by-products or illness! JimJax

  • 01/03/2014 01:34pm

    Dear JimsOso; Rather than base your assumptions on dogma you are reading in "free" websites looking to validate their own agenda, wouldn't it have been better to actually look at the study itself to figure out the answers to your questions? For example, I don't see any specific interest groups behind the authors of the study that would cause the concern you are expressing, and the information was very easy to find onlilne: http://www.nature.com/nature/journal/v495/n7441/full/nature11837.html#affil-auth, Mostly wildlife agencies, which is unusual as research costs can only be written off by pet food companies creating an income from any research they do.

    I don't know who has been making you feel so uneasy about pet food companies doing research. Yes there are some bad studies, and those are the most popular to special interest newsgroups online, including the one you are quoting. Does the owner of the group have any real training in nutrition with the appropriate credentials? And I don't mean just a purchased designation in nutrition. I ask because among trained circles, it is a well known fact that there ARE genetic changes happening in our pets causing difference between their dietary needs and those of ancestors. It also makes a big difference whether the pet you are focusing on has had a gonadectomy, with concurrent hormonal imbalance, or not.

    You aren't making these distinctions in the comments I read in your post, and I see no mention of scientific data sources that would meet your obviously high standards of good data collection. How can we take your 'critique' of Dr Mahaney's article seriously when you haven't provided accompanying data to prove your point?

    If you are up to date on genetic research you know that our genes change all the time, as do those in our pets, which was what Dr Mahaney was referring to. http://science.tgdaily.com/rt/science_v1/next-story/5a5369474376312f7035384a66564a4c33554b7154673d3d

    Dr Mahaney DOES have high credibility with his postings here, which is why PetMD has allowed him to publish articles. May I suggest you research the sources of your information a little better before latching on to unsupported belief systems you want us to validate for you?

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