Saturday, January 30, 2010
Are dogs and wolves really that similar??
In this episode:
Pet Joke of the Week: The Faithful Cat
Personal comment: Are dogs and wolves really that similar??
Transcript of personal comment from this episode of The Web-DVM:
In my personal comment tonight, I want to compare and contrast domestic dogs with their ancient ancestor, the wolf. I feel compelled to do this in light of a movement that is gaining some momentum that is directed toward treating dogs like wolves because they are essentially the same. This is most profound with regard to feeding, with some people not only themselves convinced, but vehemently trying to convince other dog owners that dogs should be fed raw meat diets. Many of people of this ilk even believe that all or most health problems of dogs arise simply because most are not fed a raw meat diet like their wolf ancestors. Others take this even further and refuse vaccines, deworming, heartworm and flea preventive...because this is how wolves live and dogs are basically wolves.
I am here to tell you today that this premise that dogs are nothing more than well trained wolves could not be further from the truth. There are physical and some behavioral similarities to be sure, but please allow me to explain that the comparison of the two species pretty much stops there - dogs and wolves are clearly separate and distinct species.
Let us begin with the wolf. The wolf is an ancient wild canid, the product of hundreds of thousands of years of natural selection, which is essentially the fact that, in the wild, only the healthiest and most physiologically well adapted to the environment survive to breed, thereby passing along to offspring only the best genes that reflect the best physical characteristics to survive. After countless generations of such natural selection, the wolf we see today is very hardy creature, physiologically capable of digesting raw meat and dealing with raw meat bacteria and parasites. They have physiological adaptations that enable them to process a diet composed largely of protein, withstand temperature extremes, are more resilient to disease, and have thick skin to better handle insect bites, mites, fleas, and ticks.
The domestic dog, on the other hand, is descended originally from the wolf indeed, from a time in our own ancient past when our ancestors found the most docile examples of wolves convenient to keep around as an easy food source in time of need, as an aid in hunting, and who knows, maybe even for companionship. This occurred presumably about 100,000 years ago, when the fossil record shows the first domestic dog bones found among those of early humans, as a representation of a novel divergent species separate from wolves and clearly living among people. This is proof that selective breeding of dogs began to occur around this time and has influenced the dog's evolution to this day, and it is this selective breeding that has made dogs so very different from the wolf.
First, since of course only the most docile and people friendly examples were logically kept by people, the wild nature of wolves was very much bred out over successive generations of dogs. Next, keeping shelter with humans and sharing their food, ancient dogs did not have an adapt or die reality imposed on them as was the case with their wild cousins. Being cared for by humans, fed cooked meat and the more diverse diet of humans in general, dogs were able to survive and breed with less physiological stress placed on them, which eventually created a species that is far less hardy and resilient than their wolf cousins, essentially a species in many ways, more like us.
Add in the highly selective breeding for the creation and maintenance of separate dog breeds that became popular in relatively recent canine history, and what have today, is an example of the opposite of the hardy wolf born of natural selection. We have instead the domestic dog born of very UNnatural selection. Selective breeding indeed gave us the physical and temperament characteristics people seeked for dogs, but with that came unwanted genetic baggage, known as recessive genetic disease that served to further weaken the species. Case in point, perhaps more than half of the canine disease I see in practice has a genetic origin.
So what does this mean when comparing the two species? Well first, the ability to deal with raw meat bacteria and parasites is far greater in the wolf than the dog. This is because the wolf is physiologically adapted to deal with raw meat pathogens with an extremely acidic stomach pH of 1 or less, poised to effectively kill raw meat bacteria and parasites. The dog, on the other hand, has a stomach pH considerably less acidic and more along the lines of people at a pH of 2.5-3. Just this week, I have treated at least 5 cases of dogs with GI disease secondary to intestinal parasites. In my career as a whole, I have treated many cases of bacterial food poisoning from the ingestion of raw meat, usually by accident, but in some cases fed purposely by owners caring for their dogs under the false notion that dogs should eat raw because they are just like wolves.
Regarding breakdown of nutrients, although wolves are omnivores, meaning that they need a mix of meat and at least some fiber and other nutrients in their diet, with the bulk of their diet coming from meat and a minority coming from the plant material present in the guts of their mostly herbivorous prey, they are physiologically adapted to thrive on a much higher percentage of dietary protein than dogs. In short, biochemically they have a greater ability than dogs to convert protein into non-protein nutrients such as fats and carbohydrates.
Dogs, on the other hand, are, like the humans they have cohabitated with for 100,000 years, are far more omniverous, needing a balance of dietary nutrients of 20%-30% protein, 10%-20% fat, 35%-45% carbohydrate, and 5%-10% crude fiber. Feeding a dog the same percentage of dietary protein that the average wolf would consume relative to other nutrients, would lead to excessive metabolic stress on the liver, kidneys, and pancreas among other problems.
If I have not yet convinced you that wolves and dogs are very different, let us compare their DNA. The dog's DNA sequence differs from that of the wolf by an average of 1%. On paper this does not seem like much of a difference, but if you consider that the DNA of humans and our closest living evolutionary cousin, the chimpanzee, is only 1.8%, one can understand that a difference of 1% is rather significant. If even this fact is not enough to convince you, consider that the percentage difference between the DNA of a 175 pound Mastiff compared to that of a 6 pound Yorkshire Terrier, both variants of the domestic dog, is virtually mathematically undetectable. If there is virtually no difference between the DNA of a 175 pound domestic dog versus a 6 pound domestic dog, how can we be made to believe that the dog is basically the same as a wolf from whom its DNA differs by an average of 1%?
Finally, the notion that dogs do not need vaccines, flea, tick, and heartworm preventive because wolves don't, is just absurd. In truth, while wolves seem to be more resilient to withstand the bites of fleas, ticks, and to combat infectious disease due to their hardiness born of natural selection, they would still benefit from these measures as well. For example, wolves are susceptible to infectious diseases that we regularly vaccinate dogs against, such as rabies, distemper, parvo, as they are also prone to heartworm disease. We do not hear about it or know about it, since they are certainly not routinely checked out by a vet. However the effects of not being protected from these diseases as dogs are is clearly evidenced by their relatively poor neonatal survival rates and much shorter average life spans. Respectively, only 40% or less of wolf cubs survive to adulthood, and the average lifespan of a wolf in the wild is only 3-5 years.
In summary, I urge you to not be misled into believing that your dog is merely a wolf and needs to be fed and treated as such. Wolves are a product of hundreds of thousands of years of natural selection, survival of the fittest in the simplest terms. Dogs, while originally descended from the wolf more than 100,000 years ago, have evolved into a less wildly adaptive, separate and distinct species from breeding under the care, shelter, and diet of humans, then later very selectively bred into distinctive and unique breeds. All of this resulted in domestic dogs being generally a less hardy species than wolves, requiring a more diverse and cooked diet, having a greater susceptibility to the elements and infectious disease, and being prone to genetically inherited disease. They are little more like wolves than humans are like chimpanzees.
That is our show for tonight. Please help us continue our discussion by visiting our blog at webdvm.blogspot.com, where comments posted there will be read and addressed in my live broadcast at BlogTV.com this Sunday evening at 7:30 pm. Please tune in next week when I will be discussing canine and feline nutrition more indepthly, including a bit more on the feeding of raw meat and the evidence we have for why it is a bad idea.
Dr. Roger Welton is the President and chief veterinarian at Maybeck Animal Hospital in West Melbourne Florida, as well as CEO of the veterinary advice and health management website Web-DVM.net.