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Are Dogs Carnivores Or Omnivores?

Updated on July 31, 2014
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The debate continues as to whether dogs are still carnivores or have evolved into omnivores. We’ve known for years that they’re able to digest carbohydrates. And there’s interesting speculation about when and how that occurred.

Theories are that our prehistoric ancestors took to throwing food out to prehistoric canids that lurked in the shadows beyond the campfire because A: they felt sorry for them, or B: because they didn’t want to be eaten themselves.

For thousands of years man and beast saw a peaceful coexistence gradually evolve into a relationship and thus the dog became domesticated. They became valuable as hunters, herders, haulers, protectors and BFF. Our forebears loved the little guys and readily shared their food with them…unless there wasn’t enough meat to go around. Sorry, Boomer, here, have a piece of bread.

Over the centuries, apparently, the dogs were able to keep the non-flesh stuff down and, in fact, adapt a gene that enables starch digestion. So in the late 19th century when commercial dog food arrived on the scene, grains were a major component of the kibble.

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Let’s fast forward to today. I wondered if by digestion they meant: able to convert food into nutrients that could be absorbed and assimilated by the body, or simply be able to ingest it, live through it, and excrete it.

Our dogs regularly swallow non-food items and poop them out. Since they pass through the entire digestive tract, but are not absorbed or assimilated, are they still digested? Most definitions of digestion say “absorbed and assimilated.” The Bing definition also includes “or excreted.”

Take your pick. I find the Bing definition intriguing. That’s because I also wonder why the manufacturers’ feeding instructions vary so much between grain-based and meat-based feeds.

A typical grocery brand that starts with whole corn, contains other forms of corn such as corn meal or corn gluten meal, and uses other grains such as wheat, sorghum, and soy, suggests 6 to 8 cups a day for a 100 pound dog.

A typical grain-free dog food that contains none of the above suggests 3 ½ to 4 ½ cups a day for that same dog.

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Dogs on the grocery brands typically produce large volumes of stool, which are occasionally soft and difficult to pick up, while dogs on grain-free foods typically produce “little cigars” that are easy to pick up. Flatulence commonly is a major issue with dogs on the grocery brands. They can clear a room quickly, can't they?

If they efficiently absorbed and assimilated the grains, why would they (A): need to eat twice as much as meat-based feeds, (B) produce so much more waste, and (C) be so gassy? Perhaps a Board Certified Animal Nutritionist will read this and comment below with an easy-to-understand answer.

But that’s not the only reason why I’m personally on the side of “they’re carnivores.” I’ve read that DNA studies prove the dog descended from the timber wolf (or gray wolf, depending upon your source) anywhere between 30,000 and 100,000 years ago (depending upon your source), give or take a millennium or two. Domestication began around 15,000 years ago.

Some scientists and lay persons opine that the dog has evolved into an omnivore, others don't. I still have a hard time accepting the omnivore position because their “carnivore’s anatomy and physiology” haven’t evolved. When you tour the entire alimentary tract of the dog, it sure looks like a carnivore’s alimentary tract. Let’s tour together.

It Sure Looks Like A Carnivore's Digestive Tract

Let’s start with the saliva, that enzyme-rich juice that begins to break down food before it reaches the stomach. There’s a specialized enzyme called amylase, that's entrusted with the job of breaking down carbohydrates into sugars.

Humans are omnivores and our saliva is equipped with it, as is the saliva of herbivores such as horses and cows. Carnivores lack amylase in their saliva, and so does the dog. I think we have to put a check mark in the “carnivore” column.

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Now let’s look at the teeth. Omnivores have a variety of teeth. Some are broad and sharp (incisors) for cutting, some are pointy (canines) for tearing, and others are flat and boxy (molars) for crunching and crushing. Herbivores have incisors and molars, but no canines. The dog has a few incisors in front, but everything from the canines back is narrow and pointy. I think we have to put another check mark in the “carnivore” column.

How about the way we chew? Humans and herbivores chew up and down and side to side, albeit more pronounced in the case of herbivores. Dogs (and cats, which are obligate carnivores) can chew up and down only. Do you agree on another check mark in the carnivore column?

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Let’s compare gastro-intestinal tracts. We have relatively small stomachs and a relatively short intestinal tract because we consume small but frequent meals. Herbivores have a GI tract that typically is about 10 times their body length because they’re pretty much grazers. Horses have a digestive tract about 100 feet long.

Ruminants (cud chewers such as cows, deer and other hoofed animals) need four-chambered stomachs to break down their food, plus they need to regurgitate and re-chew it (the cud), mixing it with more amylase-rich saliva before sending it back to their stomachs for additional processing.

Then they have this long intestinal tract to facilitate the relatively slow absorption of nutrients from the forage they’ve been eating almost constantly.

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Dogs have a relatively large stomach and shorter intestinal tract because they’re adapted for eating larger, less frequent meals.

Also, their digestive juices are highly acidic to enable the stomach to break down meat quickly so that their relatively short intestinal tract can absorb the nutrients before they’ve had a chance to exit the dog.

The dog’s strong digestive juices also kill bacteria that often contaminate raw meat. That’s why foxes and other wild canids can bury (cache) leftover meat, then dig it up and eat it a day or two later (after it really ripens). Eeeww!

There are often pet food recalls associated with salmonella contamination, but the threat is more serious to people than the dogs. A healthy dog won't be affected by the salmonella for the reason stated above.

In fact, though, a healthy adult human probably won't either. Salmonella poisoning in healthy adults usually produces mild symptom that are dismissed as "I must have eaten something that didn't agree with me." It's a different matter for the very old, very young, or those with compromised immune systems, though.

It’s also why your dog…when he comes home from doggy daycare and you’re upstairs changing clothes and taking care of other business…can eat that raw hamburger that’s been thawing on the kitchen counter all day and not get sick.

One other thing, in the form of a question: if you look in the dog’s small intestine, guess what you’ll find? Answer: amylase. A little late for that, isn’t it? I wonder how much nutrient from carbs can be absorbed in the short time those carbs are in the intestines? Can I get an Amen for another check mark in the “carnivore” column?

And look at the lifestyles! Ungulates stand around all day alternately chewing vegetation and cud, eventually moseying on over to the next patch of forage. The only exercise they get is trying to evade predation (skills that remain works-in-progress) by those pointy-toothed, amylase-challenged carnivores with the relatively large stomachs but otherwise relatively short digestive tracts.

The carnivores, on the other hand, have to hunt for and bring down prey usually several times their own weight, patrol and defend a territory, compete for and defend a mate, and maintain discipline and decorum within the pack. I’m not a nutritionist, but I’d bet that would be tough to do on a diet rich in salad. Allow me that one for the “carnivore” column?

My scorecard has it 5 to 0 in favor of “they’re carnivores.” How about your scorecard?

Here’s a theoretical question: If you dropped a dog off a hundred miles into the deep woods, do you think he’d browse for forage or hunt for game? I believe he’d hunt and, if unsuccessful, may resort to eating vegetation.

But I wonder how well he’d do and how long he’d survive on such a diet. Escaped dogs that evade capture for weeks often are trapped or otherwise apprehended in a somewhat emaciated condition. Could they survive for months or years if vegetation were a significant part of their diet?

The debate is an interesting one, isn't it? But in the scheme of things, pretty insignificant. No matter which side of the debate we're on, we can all celebrate the domestication of the dog, reflect upon his importance in our daily lives, and his status as our BFF.

WHICH SIDE OF THE DEBATE DO YOU COME DOWN ON?

Do You Believe That Dogs Are Carnivores or Omnivors?

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    • tillsontitan profile image

      Mary Craig 3 years ago from New York

      This was a very interesting hub regarding a question that's been going around for a long time and in spite of your well researched information will continue to go around for a long time. I don't know if I would ever go strictly with an all meat diet but I certainly look for the highest grade dog food with little or o filler.

      I fear never the twain shall meet! However, more important is the health of the dog.

      Voted up, useful, and interesting.

    • Bob Bamberg profile image
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      Bob Bamberg 3 years ago from Southeastern Massachusetts

      Hi tillsontitan, nice to see you. I agree that the debate will continue and I agree with your poll choice. I don't believe they're true carnivores, like cats and ferrets, who will suffer cardiomyopathy or retinal degeneration from a diet deficient in taurine, which is only available in meat.

      But I can't get beyond the dog's anatomy and physiology. Everything, to me anyway, points to carnivore. They don't have a discriminating pallet and will usually eat pretty much anything you put in front of them...and what you don't put in front of them, such as buttons, coins, rocks, socks and turds.

      Although they'll eat a variety of stuff, I don't think that classifies them as omnivores as much as it does opportunists. If I had to classify them, I'd call them carnivores because of their A&P, but I'd rather see a third category that falls somewhere in between.

      You're right, though...the important thing about what to feed a dog is that he's fed something that supports his health. Thanks for stopping by, taking the poll and voting. Regards, Bob

    • DrMark1961 profile image

      Dr Mark 3 years ago from The Beach of Brazil

      Lots of good info,but I am still an "omnivore that prefers meat" kind of guy. My dog is on a raw all-meat diet, but when the butchers dont have any parts n´stuff (faces, throats, lungs, kidneys, and anything else humans dont eat) I feed cheap dog food, and she does fine. (Of course there is a lot more to clean up in my yard.)

      Thank goodness even our cheap foods are not as bad as that Ol´Roy label in your hub. Corn Gluten Meal, mmmmm!

    • Suhail and my dog profile image

      Suhail Zubaid aka Clark Kent 3 years ago from Mississauga, ON

      Well, my dog, a Kuvasz is a meat eater and is on a high quality Orijen 6 pack fish meal. I also feed him boneless chicken thighs and he steals lots of scraps too. But his preference is always to go for meat.

      I am sure he is a carnivore.

      Excellent hub and point well argued and put forth.

    • Bob Bamberg profile image
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      Bob Bamberg 3 years ago from Southeastern Massachusetts

      Thanks for the comment, DrMark1961. I'm sort of with you. But, I think because of their A & P they have to be classified as carnivores, while pragmatically they're omnivores, but only because we make so many non-meat choices available to them.

      I believe that the reason you have to pick up so much in your yard when you feed cheap food is because they really can't assimilate many of the non-meat ingredients. You have to feed twice as much and it just ends up in your yard.

      "Omnivore that prefers meat" has a nice ring to it, but we've got to come up with a 3 or 4 syllable single word. Meatfirstivore may be a possibility, although my spell checker doesn't like it.

      We have a supermarket here that caters to a number of cultures and I've seen pig's ears and beef trachea packaged for human consumption, which is the closest I've seen to a throat. I'll bet your shopping list often reads like a Stephen King script. Thanks for stopping by. Your comments always stimulate interesting discussions. Regards, Bob

    • Bob Bamberg profile image
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      Bob Bamberg 3 years ago from Southeastern Massachusetts

      Hello, Suhail, nice to see you again. You feed your dog well, in fact, I'd gladly accept a dinner invitation from you. Boneless chicken thighs is one of my favorites. I like to coat them with mayonnaise, parmesan cheese and Italian seasoned bread crumbs then bake them. Thanks for stopping by and for the kind words. Regards, Bob

    • DrMark1961 profile image

      Dr Mark 3 years ago from The Beach of Brazil

      I think the butchers all know me as the "cow lips" guy! (As in "Hey, got any cows lips for sale today?"). I think that is my meatfirstivore´s cow part of choice. I bet Stephen King would love to have such a cool nickname!!!

    • rebeccamealey profile image

      Rebecca Mealey 3 years ago from Northeastern Georgia, USA

      Interesting. My dogs love to eat grass, but they usually throw up afterwards! I just decided to ignore their little "habit" . Thanks for sharing your knowledge.

    • Bob Bamberg profile image
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      Bob Bamberg 3 years ago from Southeastern Massachusetts

      You just got yourself a new nickname, CowLips1961...but if it's OK with you, I'll just call you CowLips for short lol :) :) :)

      Hello, rebeccamealey, nice to meet you. The "dog eats grass then throws up" paradigm is an interesting one. One theory has it that their stomach is upset so they're purging themselves. I just don't think they're smart enough to have made that connection.

      My favorite is that the grass irritates their stomach lining and the stomach is ejecting it. If you run your thumb and forefinger along a blade of broadleaf grass, you'll see that it feels like fine sandpaper. That makes more sense to me.

      I also like the one that says they eat grass for the same reason they eat socks, rocks, coins and other non-food items. Who knows. Thanks for stopping by and commenting. Regards, Bob

    • Romeos Quill profile image

      Romeos Quill 3 years ago from Lincolnshire, England

      An interesting article; was reading only today about the usual foods which were listed as toxic to dogs, such as yeast dough, raisins/grapes, chocolate, onion, mushroom, peaches, alcohol etc...

      I think that your proposed third category might cover your question ( they are carnivores, but not true carnivores ). A good topic of debate, and informative.

      Thank you;

      Kind Regards,

      Romeo's Quill

    • Bob Bamberg profile image
      Author

      Bob Bamberg 3 years ago from Southeastern Massachusetts

      And the debate rages on, Romeo's Quill. Many people I talk to are passionate about their position. I acknowledge that they'll eat vegetation, I just don't know if they get any sustainance out of it. They eat a lot of things, are able to pass it, but surely don't get any nourishment from it. Thanks for stopping by and commenting.

    • Romeos Quill profile image

      Romeos Quill 3 years ago from Lincolnshire, England

      You're welcome.

      P.S. The angelic Jackie Lynnley has surreptitiously lifted you upon her wings and has paraded you throughout HP town like a human flag ( because she's nice like that ), and has carved a pilgrimage trail of new readers for specially chosen Hubbers of note, in her and Faith Reaper's hugely successful ' Hug of the Day ' series. Lucky 'ol you!

      Best Wishes for a pleasant weekend,

      R.Q.

    • Bob Bamberg profile image
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      Bob Bamberg 3 years ago from Southeastern Massachusetts

      Thanks for the heads up, R.Q. It's humbling to be singled out like that, and I sure do appreciate it.

    • DDE profile image

      Devika Primić 3 years ago from Dubrovnik, Croatia

      Great hub about this question and you explained to perfection. informative, useful and very interesting indeed.

    • Bob Bamberg profile image
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      Bob Bamberg 3 years ago from Southeastern Massachusetts

      Thank you for the kind words, DDE, I'm glad you enjoyed it. Thanks, also, for stopping by and commenting.

    • MG Singh profile image

      MG Singh 3 years ago from Singapore

      Added a lot to my knowledge . Thanks

    • Bob Bamberg profile image
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      Bob Bamberg 3 years ago from Southeastern Massachusetts

      Thank you for dropping by, MG Singh, I'm glad the hub was helpful.

    • profile image

      Rer 2 years ago

      Absolutely disagree with most of you. An omnivore is an animal that can survive on either plant or prey insect/fish/animal diets. dogs are most certainly omnivores just like the maned wolf... http://en.wikipedia.org/wiki/Maned_wolf

      Just because an animal has carnivorous traits or looks, does not mean it's a carnivore. Sure you can feed your dog an all meat diet, but they do best with a mix of meat and plant matter. They have evolved along side humans for 30,000 years by eating mostly what we eat.

    • Bob Bamberg profile image
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      Bob Bamberg 2 years ago from Southeastern Massachusetts

      Hello, Rer, thanks for stopping by. Dissenting opinions are always welcome and they hopefully spark some lively debate, but in my opinion your rebuttal is weak.

      It's known science that dogs (and cats) have no nutritional requirement for carbohydrates, and there's no indication that they do best on a mixture of meat and plant matter.

      Citing Wikipedia as an authoritative source is also weak because it is not an authoritative source. Your final sentence, in my opinion, is short-sighted, ignoring that over the millennia, millions of predators occupied millions of square miles of wilderness untouched by humans.

      The few that scavenged scraps from around camp-fires feed our romantic notions, perhaps, but it's doubtful that they "earned a living" that way.

      Reasonable people can, and will, disagree, and that's fine. Each can come away with a look from another perspective. Whether or not they choose to subscribe to any of the opposing viewpoint is not assured, and certainly none of us has the market cornered on knowledge.

      Thanks, again, for reading the hub and taking the time to comment.

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