The Omnivorous Dog Part 2: Macro Nutrient Requirements Don’t Lie

Last time, I gave you a very generalized overview on the dog’s [very limited] ability to physically digest plant materials.

This time we’re going to look at the macro nutrient requirements of the omnivorous dog.

As you know, macro nutrients are those nutrients required in the greatest amounts: protein, fats and carbohydrates.

Proteins and fats can be obtained from plant and animal sources with plants containing only a fraction of these nutrients when compared to animal sources.

Carbohydrates can only be found in plants.  Absent human adulteration of foods, by slathering on sauces, breading and other such unhealthy additions, you will not find a single carb in body or bone tissue of animal source foods.



In the case of the omnivorous human, the carbohydrate requirement is 3-4 times the requirement for protein, with fat being the nutrient required in the least amount.  The primary energy source for the human is the carbohydrate, the nutrient required in the highest amount.  Good carbs come from unadulterated fruits, vegetables and whole grains – not breaded fried chicken or Cheetos.  It is possible for the human to meet all 3 macro nutrient requirements just by targeting the carbohydrate requirement as long as whole grains, legumes and/or nuts (higher end protein sources for plants) are included in the mix.  If the world were to suddenly lose all meat sources, the human would be just fine on a diet of plants alone.



The dog has no nutritional requirements for carbohydrates.   Protein and fat together make up 100% of the  macro nutrient requirements. Unfortunately, very little research has been done to determine just what the protein and fat requirements are [more on this at another time].   The primary energy source for the dog is fat, which means fat (animal source) should be the nutrient required in the highest amount, but refer back to the lack of research.  Just like the human can satisfy all his nutritional requirements from one type of food (plants), so too can the dog – eating other animals.   If all plants disappeared from the planet, the dog would do just fine on a diet of other animals alone.  Remove all meats from the world (as well as all manufactured supplements used in vegetarian and vegan dog food diets), and the dog would die.  End of story.




That the ‘omnivorous’ dog physiologically tends highly carnivore, due to his digestive abilities and nutrient requirements, has been known since the dog was first used as a laboratory animal.  The earliest published scientific paper I have been able to find stating this was written by G. R. Cowgil in 1928.  The pet food industry, AAFCO, the NRC, all serious text books and reference material provided to hopeful vet school students … none deny that carbohydrates are not required by the dog.  It is also agreed that the most efficient source of all required nutrients is animal tissue.

Despite the facts agreed to by all, commercial dog foods continue to contain more carbohydrates than protein and fat combined.   Here’s how to calculate the carbohydrate content of your dog food:  From the Guaranteed Analysis, add the protein and fat content together, then subtract that number from 100.  The result will be the carbohydrate content. [This only works on kibble.  Canned foods use a different method.]  Go ahead and do the calculation, I’ll wait!

OK, so you’ve calculated the carbohydrate content of your dog’s food.  Is it more than the combined content of protein and fat?  

Knowing what you now know; that the dog’s ability to digest plant materials is extremely limited and that the dog has no nutritional requirement for anything plants – remember, this includes fruits and vegetables – have to offer, how does this make you feel about what you’re feeding your dog?

Next time I’ll show you how this all slipped by you in the past.  It isn’t that your research was faulty, it’s that you were asking the wrong questions.   I’ll show you where to look and what questions to ask.  



Until then, here’s your homework:  Familiarize yourself with Nutritional Requirements of Dogs and Cats (NRC 2006).  This book is the impartial cliff notes of all available research, at least up until publication.  It can be purchased on Amazon, which I highly recommend,  but most pages are available free on Google Here.  If, as I think you may, you go right to the Carbohydrate section, pay very close attention to what is NOT said.  I’ll give you a hint:  The same deficiency, pun intended, is not found in the sections on protein and fat. 






The Omnivorous Dog Part 1: Digestion of Plants

Is the dog an omnivore?  I guess is it depends on your definition of “omnivore’.

To most of us, an omnivore eats both meat and plants.  Alas!  This ‘definition’ is incorrect!

Any organism can eat any food, but whether or not a particular organism can reduce a food item to the point where nutrients can be extracted is an entirely different matter.  In the case of the omnivore, the ability to reduce plants to the point nutrients can be extracted is the wildcard.




Fun Fact For You:  There is no animal on the planet, visible to the naked eye, that is able to digest (and for our purposes, “digest” will mean reduce to the point nutrients can be extracted) plant materials.  Not even an herbivore has the ability to do this!

Specialized enzymes start to break down the rigid walls of plant cells, making them easier to consume – not by the animal who ate the plant – but the bacteria that reside in the animal’s digestive system.   These bacteria are the only animals in the world that have the ability to digest plants at the cellular level.

The herbivorous cow has both enzymes and plant eating bacteria in his saliva.  This means that at first bite, digestion of plant materials are well underway – not just reducing the size of food particles through chewing, but actual digestion of plant materials at the cellular level as food particles are coated with plant cell reducing agents.  Despite this jump-start, the cow has 4 stomach chambers – think of them as fermentation chambers – where massive amounts of bacteria feed on ever reduced food particles.  Even then, it’s not enough, ergo the cow’s ability to regurgitate stomach contents back to the mouth for further chewing /particle reduction (the term is rumination) which is then swallowed back down into the fermentation chambers. Enzymatic and bacterial action continue through the intestines right up to the point that ingested plant material becomes a cow patty on the ground.



The omnivorous human does not have the plant cell reducing powerhouse combinations of enzymes and bacteria of the herbivore.  For this reason, the human can only eat certain plant materials – fruits, vegetables, certain grains and roots, and others along those lines.  Enzymes, at the very least, and limited bacteria depending on the published research reviewed, starts reducing the plant material at the cellular (cell wall) level in the mouth via the saliva.  As the food particles are being reduced through chewing, they are also being coated with enzymes (possibly limited bacteria) which begins opening the plant cell walls for…  the bacterial population residing in the stomach.  By the time the plant material leaves the stomach, it’s pretty well broken down, but just to be sure, more enzymes and bacteria continue the digestion process in the intestines, ending at ….  well I think you can figure it out.




The omnivorous dog has no enzymes or bacteria in his saliva to start the process of digestion of plant materials.  He has no plant cell wall reducing enzymes or bacteria in his stomach.  Only at the point the food leaves the stomach and enters the intestines does any mechanism for the digestion of plant materials appear – enzymes and bacteria.  The food has passed through nearly half of the digestive system in a form (intact cell walls) that contributes absolutely nothing to the nutrition of the dog.  Not even the herbivore’s digestive system is efficient enough to digest all plant material when the process starts in the mouth with saliva, but we expect the “omnivorous” dog to be so efficient he can fully digest plant materials in the time it takes to pass through the intestines and exit the back-end.



The natural dog, free from human interference (think feral, not Fifi on the couch), tends toward 3 types of plant materials:

  1.  The stomach contents of prey.    These plant materials would be in various stages of digestion in the animal consumed. Enzymes and bacteria in the dog’s intestines would be able to do the ‘finishing’ digestion and extract nutrients from the plant materials.
  2. Rotting fruits and vegetables.  The cell walls of these plant materials are broken down through the process of decomposition.  The breakdown of the cell walls allows the intestinal enzymes and bacteria to extract nutrients from the material, however, significant nutrient loss has occurred through the process of decomposition.
  3. Fecal matter of herbivores.  Because no digestive system is 100 % efficient, partially digested food exits the back end of the herbivore.  Refer back to partially digested – all the intestinal enzymes and bacteria in the dog’s intestine have to do is finish the digestion.

OK, show of hands:  How many of you will chase down a rabbit, rot fruits and vegetables in the sun or collect Road Apples (the end result of horse digestion) to provide the plant materials most appropriate to your dog’s digestive abilities?  Anyone?



It’s much more civilized, socially acceptable and much less disgusting to stick to peas, carrots and green beans, isn’t it?  Bummer is, cooking them makes them more ‘digestible’ to the dog, but most of the nutrients leach out in the cooking process.  Raw is out of the question because the dog, more particularly the chemicals and organisms in his intestines, simply can’t extract enough nutrients to make it worthwhile.  Yes, you can grate raw, and more nutrients will be extracted, but it still falls short of nutritional requirements.

If all one considers is the presence of plant material specific enzymes and bacteria in the digestive system, yes, dogs are omnivores.  However, a more correct description would be that dogs are Limited omnivores.  The dog has no ability to extract sufficient nutrients from plant materials to survive on a diet of plants alone or as the majority of the diet unless those plant materials are highly processed, so much so that they have lost all or most of the possible nutritional value.  No one knows this as much as those who feed their dogs vegetarian or vegan – just look at their collection of supplements!

We’re going to continue the discussion of the omnivorous dog through his macro nutrient requirements in the next installment.  I just want you to consider what I’ve said here and how it applies to how and what you feed your dog.  I also want you to do a little research:  Look up digestion of the cow and human, 2 critters that have been studied extensively without political, moral or marketing bias.   You can’t do the same lookup for dogs because most of our Internet available information is based on a belief that dogs didn’t eat before the creation of commercial dog food where plant materials passed meat as the dominant ingredients.  I’ll give you some resources later on, once we have finished our discussion of the omnivorous dog.


Until then….

Humans and dogs have existed separate and together for millennia and tales of friction are legion.   Can we all agree that stories of feral dogs, either individually or in packs, taking down small or baby livestock is the primary complaint?  If dogs are natural and human-like (more efficient) omnivores, how come there are no accounts of packs of feral dogs taking out crop fields?  Think about it.