There are two ways to look at the issue of diet for a species.
I call one of them the empty bowl method. You ask yourself what you need to fill that bowl with to assemble all the nutrients that the species needs and will thrive on, and then you do your best to get all those various substances together in the right amounts and make it palatable. This is the method used to formulate kibble.
I call the other the evolutionary model. You ask yourself what the species evolved eating during times of abundant habitat and high reproductive rates, and then seek to reproduce that.
In the real world, people tend to fall somewhere between those two approaches, with most landing very, very far over toward the "empty bowl" method, and those of us in the holistic camp falling substantially closer to the evolutionary method end.
If we want to feed according to the evolutionary method, we have to ask some basic scientific questions:
What species is the dog? What animal's evolutionary history do we look at to determine its natural diet? (And by the way, "natural diet" is not a marketing term, it's a scientific term meaning the diet the species eats in the wild during times of abundant habitat and food supply, and without the intrusion of humans. In other words, just because bears raid trash cans does not make nacho cheese-smeared paper part of their "natural diet.")
In what ways did the natural diet change over time and geographically?
What non-diet elements, such as hibernation and normal activity levels, might interact closely with diet and thus impact our understanding of the data?
What effects do scientists observe as indicating poor habitat/food availability for this species? In other words, when researching this species, what things seem to happen that tell scientists there was trouble in paradise as far as food supply goes?
Taking dogs as our species in question, we have to answer, what species is the dog? Dogs are a domesticated variant of the grey wolf, canis lupus. Their taxonomical classification is canis lupus familiaris. They are the same species as the wolf. They can interbreed and produce fertile offspring. They are more similar by far to the wolf than any other canid species, such as the coyote or the fox.
Wolves, including the domesticated wolf we call the dog, are classified biologically as being in the order carnivora. There is absolutely, positively no scientific debate, dissension, or discussion on this issue. Why, then, do so many “experts” say the dog is an omnivore?
The only reason any "expert" would ever say a dog is an omnivore is because he or she is an "expert" in a field other than the taxonomy of a species. No wildlife biologist or zoologist would ever tell you a dog or wolf is not a carnivore. But pet food manufacturers will tell you dogs are omnivores, because to them, "omnivore" means an animal who can eat both animal and plant foods. The problem is, if that were the scientific definition of "carnivore," there would be no carnivores on this earth. Why, then, is there so much disagreement on this issue?
I believe it is because we don't share a common definition of our terms. Scientifically, the species of the dog is canis lupus familiaris. The dog is a grey wolf. The grey wolf is a carnivore. Those things are crystal clear in a scientific sense, but hearing this distresses many people, because they are using the more common meanings of those words, and in common usage, obviously a dog is not a wolf and they are not "carnivores." In common usage, a "carnivore" is an animal that eats only meat, and a wolf is a wild animal. And so we go round and round arguing, and getting nowhere.
Going back to our list of questions, we now look at the natural, evolutionary diet of the grey wolf. To do that, we look at the research and writings of the most respected, best-known wolf researcher in the world, David Mech. We crack open his book The Wolf: The Ecology and Behaviour of an Endangered Species, where we find that worldwide, all evidence tells us that the wolf, today and in the past, ate mostly large ungulates (deer, gazelle, and similar prey), with a small amount of hare and beaver filling in seasonally and regionally. They ate almost no vegetation, not even the stomach contents of their prey, although "almost none" is not "none."
Some carnivores eat a lot more vegetation than the wolf, and a few, such as the big cats, eat less. One carnivore eats only the trace amount of animal protein that comes with the bugs that live on the vegetation it eats... the panda bear. Pandas took an odd evolutionary turn as they adapted to their vegetarian diet, but this quirky adaptation has left them extremely vulnerable in their environment, and the only carnivorous mammal that literally eats every waking hour. They are an anomaly in their order, but they do go to show that the scientific definition of "carnivore" obviously is not the same as the popular definition, or a panda bear couldn't be a carnivore.
From Mech we know that the natural diet of the dog is the flesh, organs, viscera, fat, bones, hide, and blood of large ungulates, with a small amount of hare and beaver thrown in. This prey was eaten on the ground, and with the hide and blood. The prey had just been through a period of extreme stress as it was being chased and caught. The wolf will eat it when it's freshly killed, or even still alive, but will also come back and eat it later, when it's been dead for a while, and is partially rotten and crawling with maggots and microbes, and will even eat it frozen. Wolves will also bury their prey, and dig it up and eat it much later, covered with dirt. They will eat and go back to their dens and regurgitate food for pups, and injured or old wolves.
Which brings us to the final question we need to consider when taking the evolutionary approach to canine diet: What effects do scientists observe as indicating poor habitat/food availability for this species?
The red flags for scientists for inadequate food supply for a species are a fall-off in reproductive rate and an increase in parasitization and disease. Predators in good habitat with abundant space and a good supply of food and water reproduce at a high rate and have a low rate of parasitization and disease. These things are the "gold standard" of evaluating species success, and allow us to know on what diet the species is most successful.
And this, of course, brings us right to the topic of how to make our pets (in the context of this discussion, our dogs) resistant to disease and parasites, and how to produce optimum health in our dogs. We, too, need to find out what diet produces the greatest reduction in parasitization and disease rates in our dogs, and, if we are breeders, the best reproductive health.
One aspect of health is dental condition. According to the American Veterinary Dental Society, "80 percent of dogs and 70 percent of cats show signs of oral disease by age three. In fact, oral disease is the No. 1 health problem diagnosed in dogs and cats."
Wild animals in the wild, who are not debilitated by habitat destruction, over-population, or some other adverse influence simply do not have a vast majority of the members of the species having dental disease by the age of three. A proper species-appropriate diet will keep the teeth of any species clean, barring some kind of genetic or habitat problem. There is simply no way a species is going to evolve over hundreds of thousands of years to inevitably have serious dental problems at a young age, with the attendant risks of kidney and other organ problems. It defies logic. It also defies evidence.
Feral cats have less calculus than pet cats. Raccoons in unpopulated areas have fewer cavities and less dental problems than raccoons in populated areas. In the Journal of Veterinary Dentistry, researchers said that in zoo bears, "The composition of the food and feeding management are most likely responsible for the lack of natural cleaning and the resulting plaque and calculus formation."
The Journal of Zoology and Wildlife Medicine compared the dental health of zoo bears and wild bears, and concluded, "Stereotypical behavior like cage chewing is a suspected cause of canine tooth and secondary alveolar lesions, whereas a nutritionally inappropriate diet and inadequate opportunities for tooth-cleaning activities are responsible for the lack of natural cleaning and the extensive calculus formation that results. "
Holistic veterinarian Kim Henneman, DVM, gave me permission to post this:
"At the recent Western States Vet Conf (one of the biggest in the US), I attended the lecture on Mountain Lions and Grizzly Bears out of curiosity. The veterinarian was a gentleman from Canada who has worked on these animals for years including captive raised in zoos and wild animal parks (mimic natural environment) and research on the wild animals. He showed us photos of the teeth of 9-10 year old cougars (they know because they were tagged at birth) in the wild that look like they just erupted (white, no tarter, no gum irritation) as well as cougars that were kept in game preserves...same thing."
DA Crossley, a British veterinary dentist and joint editor of the British Small Animal Association Manual of Small Animal Dentistry, states: "The body's natural control methods basically revolve around physical removal of plaque bacteria during eating, the antibacterial chemical and flushing actions of saliva and a cellular response involving 'neutrophil' white blood cells. When animals feed in the wild they rarely develop a serious level of periodontal disease unless they are debilitated in some other way. By feeding animals unnatural foods we encourage plaque buildup and the development of periodontal disease."
Obviously, we can use dental health as one of the criterion for evaluating the overall condition of our dogs. It's not the whole story, as many sick dogs have healthy mouths and many healthy dogs have a tendency to form tartar due to changes to jaw structure caused by human selective breeding (this is the case with many toy breeds or breeds with extreme head shape). And equally obviously, diet is not the only factor that affects dental health. But it should be the first factor we look at once structural problems are taken into account. To discuss canine dental health without talking about diet is scientifically bankrupt, and to discuss diet without discussing the natural diet of the species is the same.
This doesn't mean that there is no other way to feed a dog than raw. It doesn't mean that everyone "must" feed a natural or evolutionary diet to their dog to keep them in good health. But it DOES mean that we need to THINK ABOUT THESE ISSUES when we are thinking about the interplay of nutrition and health. We can't just ignore scientific evidence and definitions, we can't refuse to look at the story behind the story being told to us by veterinary dentists and pet food manufacturers. We can't just look at the fluffy little dog on our sofa and say, "This is not a wolf! This is not a carnivore!" We have to look behind the obvious and find out if what we believe and feel is, in fact, supported by the evidence.
Once we've done that, we'll be in a much better position to evaluate the health of our dog and the many factors that affect that health. Genetics aside for the moment (since once the dog is conceived those are out of our control, and most dog owners are not breeders), diet is the absolute cornerstone of good health. If we are, for whatever reasons, not feeding a species-appropriate diet to our dogs, and/or if they have special qualities, such as an extreme jaw shape, that adversely impact dental health, we need to use the information we have available to us to compensate for those factors.
This might mean we need to brush our dog's teeth, it might mean considering changing the diet, it might mean they need professional dental cleaning, it might mean we need to dig deeper and see if they have an immune problem (more commonly a cause of oral problems in cats, but can be the cause of chronic canine dental problems sometimes). It might mean we need to consider using supplements or drugs that will help rectify nutritional or genetic deficiencies or problems. It might mean dental surgery to correct a jaw problem. But unless we ask the questions and look at the big picture first, it will be hard to know what might help.
Very, very few people feed their dogs a true evolutionary diet. Even if they feed whole ungulates to them, as is the case with some dog owners and many wolf owners and wolf parks, the element of the hunt has been taken out of the equation. Absolutely fresh and/or still-living prey is rare or not available at all. (For dogs, anyway - I know a lot of snake keepers who feed live prey to their snakes.) Even if we feed whole prey, odds are it did not live its life eating its natural diet, and it most likely didn't have a completely natural lifestyle, either. Both those factors change the nutrient profile of the food animal.
Most of us who feed a raw homemade diet to our dogs are feeding a semi-natural diet. With varying degrees of success, we're attempting to mimic the natural diet as closely as we can, using the research done by the "empty bowl" camp to fill in the nutritional gaps. We feed raw if we're comfortable with it and if our dogs do well on it and we have a safe source of raw meat. We feed little or no grains, as grains are not a natural food for carnivores (or herbivores, for that matter, except seasonally). Some of us give bones and some use supplements to provide the nutrients found in bones. Some of us don't like to give any supplements at all, but most of us realize that, due to the inadequacies of modern farming and the myriad of ways in which we fall short of truly reproducing the wild diet of the wolf, some supplements and "unnatural" foods can do a good job of filling in the missing dietary components or correcting imbalances in the nutrient profile of farmed meats.
Other people, equally well-intentioned and informed, recognize the limitations of food availability, money, time, storage space, or other factors, and opt to use a commercial diet. Some of these are raw, some canned or frozen cooked foods, but most are kibbled or dry foods. (There are also people who feed kibble because they have never thought about it, or because they don't really care about canine diet, but I'm guessing none of those people are reading this.)
Regardless of what we feed, we can use the information of science and research about wolves to help guide us in making good decisions, and in understanding what health effects are likely to be diet-related and diet-influenceable. Dental health is one of those effects, along with disease resistance in general, parasitization, and, if we are breeders, reproductive success. But if we don't really understand the evolution of our dogs, if we don't know scientifically what species they are, what order they belong to, what they evolved eating and how they evolved living, or what standards are used in science to determine species success, we're at the mercy of other people's interpretations and interests. We owe it to our dogs to inform ourselves, because they eat what we give them.
I can understand that someone who comes to a canine nutrition email list or forum asking what to do about dental problems in his or her dog might be taken aback when advised to feed raw bones. Even though raw meat and bones are the natural diet of the dog, and even though feeding them has become much more common than ten years ago, it's still a minority practice in most of the developed world today. And most vets will still speak out against it. But for the members of that list or forum to NOT suggest this as one approach, to ignore the dietary issue and just accept that the questioner would continue to feed her dog the exact same way she has been, would be sort of missing the "Dr. Phil" lesson: "How's that workin' for ya?" If her dog didn't have problems with doing it the way she is doing it, she wouldn't be asking for help.
And even if someone already feeds a raw diet, that doesn't mean it couldn't be changed to result in better dental health for their dog. However, it may be that this dog, like others, will not have good enough dental health from diet changes alone, and in that case, there are other things that can be done, such as brushing the teeth or supplementation. Regardless, I feel that discussing diet is the first and most obvious thing to do when asked about better dental health.
Since only an excerpt from that article is online, I will include one pertinent quote from it:
"Genetic studies show that dogs evolved from wolves and remain as similar to the creatures from which they came as humans with different physical characteristics are to each other, which is to say not much difference at all. 'Even in the most changeable mitochondrial DNA markers [DNA handed down on the female's side], dogs and wolves differ by not much more than one percent,' says Robert Wayne, a geneticist at the University of California at Los Angeles."
.... it's a very long article, but the pertinent part is here:
"The earliest remains of the domestic dog date from 10 to15 thousand years ago; the diversity of these remains suggests multiple domestication events at different times and places. Dogs may be derived from several different ancestral gray wolf populations, and many dog breeds and wild wolf populations must be analysed in order to tease apart the genetic sources of the domestic dog gene pool. A limited mtDNA restriction fragment analysis of seven dog breeds and 26 gray wolf populations from different locations around the world has shown that the genotypes of dogs and wolves are either identical or differ by the loss or gain of only one or two restriction sites. The domestic dog is an extremely close relative of the gray wolf, differing from it by at most 0.2% of mtDNA sequence.
"In comparison, the gray wolf differs from its closest wild relative, the coyote, by about 4% of mitochondrial DNA sequence14 (Fig. 4). Therefore, the molecular genetic evidence does not support theories that domestic dogs arose from jackal ancestors. Dogs are gray wolves, despite their diversity in size and proportion; the wide variation in their adult morphology probably results from simple changes in developmental rate and timing."