Carnivore vs. Herbivore vs. Omnivore

By: Dr. Sara Ritzie

There is a fair amount of debate over whether a dog is an omnivore or a carnivore.  And this debate will continue as long as marketing campaigns continue to use it in an attempt to sway you into a belief about how a dog should be fed.  When I get sucked into a discussion about this, the first thing that comes to mind is… WHO CARES????  Dogs are not like humans, they do not boast about their eating preferences or habits (vegetarian vs. meatatarian).  But then the calm logical explaining side of me takes over and I feel obliged to spell out why I truly don’t give a hoot one way or another…..

First of all, what is a carnivore? The word carnivore can be broken down into its Latin components carne (flesh) and vorare (devour).  So literally, the word carnivore means flesh eating.  Similarly, herbivore can be defined as “plant eating”.  But here’s where it gets confusing…… while herbivores generally don’t eat any animal tissue, carnivores quite commonly eat plant material (what cat doesn’t love to munch on grass?).  This gets even fuzzier when you throw in the omnivores (“everything eating”).  Animals that are considered omnivores (for example humans and bears) can fall anywhere along the spectrum of “vegetarian” to “animaletarian”.  While the panda bear is essentially a “herbivore”, the polar bear is essentially a “carnivore”.  And as if THAT wasn’t enough, some people have added extra categories:  obligate carnivore (MUST eat animal tissue), hypercarnivore (>70% of the diet consists of animal tissue), mesocarnivore (50-70% of the diet consists of animal tissue), and hypocarnivore (<30% of the diet consists of animal tissue).  HUH????  So to summarize; herbivores eat plants and don’t eat animal tissue.  Omnivores eat plants AND animal tissue, but there are exceptions where omnivores either don’t eat plants or don’t eat animal tissue (vegetarians, polar bears, etc….).  Carnivores eat animal tissue but can and will eat plant material.  I think the problem is, this is a very rudimentary classification scheme used in school by kids because it’s easy to understand. Its only purpose is to classify animals based on eating habits.  To use it in any other way is an oversimplification that is at best a marketing strategy used to promote popular nutrition fads, and at worst dangerous in that it doesn’t take into account an animal’s true nutritional needs. 

SO let’s take a step back….. from a nutritional standpoint, what is a carnivore?  Basically, a carnivore is an animal whose nutritional requirements cannot be met with plants alone.  The classic example is cats.  Cats require high levels of dietary protein.  While plants do contain protein, it is in lower amounts than animal tissues.  Taurine and arachidonic acid are essential nutrients for cats, meaning these nutrients must be provided in the diet.    A diet consisting of exclusively plants will cause a dietary deficiency in these nutrients.  It is possible however, to extract and concentrate protein from vegetable sources, and supplement with specific nutrients, to create a “vegetarian” diet that is nutritionally balanced and appropriate for a cat.  Does this mean we should be feeding cats vegetarian diets? Of course not.  It just illustrates that even in the case of an “obligate carnivore” it is possible to meet their nutrition requirements through a variety of appropriately processed (aka, DO NOT TRY THIS AT HOME) non-animal ingredients.

So what about dogs? Are they omnivores or carnivores?

If you consider phylogeny, dogs are from the mammalian order “carnivora”.  So are the obligate carnivores, cats (one vote for dog=carnivore).  And so are the ‘omnivorous’ bears.  Oh bother (one vote for dog=omnivore).

What about their nutritional needs? Unlike the cat, taurine and arachidonic acid are not considered essential for dogs.  They can obtain all the nutrients they need from vegetable sources (one vote for dog=omnivore).  Except like cats, they have higher protein requirements than people.  It is difficult to achieve their daily protein requirements from unprocessed vegetables1  (one vote for dog=carnivore).  If you look at their anatomy, they have a relatively short digestive tract (one vote for dog=carnivore).  They produce digestive enzymes such as amylase, required for digesting plant material (one vote for dog=omnivore).  Their teeth are designed for tearing (one vote for dog=carnivore), however they do have flat molars (one vote for dog=omnivore), BUT, they don’t use those molars for grinding their food, and they really don’t chew much at all (one vote for dog=carnivore). 

Alright, so we have 5 votes for dog=carnivore and 4 votes for dog=omnivore.  Is 55% enough of a majority to say the dog is a carnivore?  If we agreed they are carnivores, are they hypercarnivores, mesocarnivores, or hypocarnivores?  And if they’re anything but 100% animal tissue eaters, isn’t that basically an omnivore? Good grief…. no wonder this debate is still going on……..

All of that aside, even if they ARE carnivores, it doesn’t mean that they can’t get beneficial nutrients from plant material.  Plants provide antioxidants, fatty acids, carbohydrates, and protein.  We can combine different plant proteins and amino acid supplements to produce complete amino acid profiles.  We can use different parts of plants to customize the nutrient profiles of different formulas to tailor them to different nutritional needs.  Plants are full of good stuff that I want my pets to receive. 

The reason I so adamantly DON’T CARE if dogs are omnivores or carnivores, is because it’s an inaccurate classification system, intended to help identify species.  It’s not meant to be used for formulating diets as it gives no indication of a dog’s nutritional needs.  I care that my dogs receive the nutrients they need to not only survive, but to thrive.  I care that the food I feed is highly digestible, and has a high level of quality control.  I care that there is knowledge and research behind the formulation of my pets’ diets.  I KNOW that they are getting all the nutrition they need from a variety of ingredient sources, including both plant and animal origin.  So what difference does it make which arbitrary column they belong in?

1.  E. Kienzle and R. Engelhard. A field study on the nutrition of vegetarian dogs and cats in Europe. From Proceedings of Sixth Workshop in Pet Food Labeling and Regulations. p. 139.


One Response to “Carnivore vs. Herbivore vs. Omnivore”

  1. Denise says:

    Hurray, for a change a voice with sound reasoning!! I get tired of the whole debate. Increasingly perceptions of what pet’s need is being moulded by clever marketing and poorly conceived and ill informed blogs! Of course all the hype is on the recipe or ingredients, forget about nutrient value!

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