Raw food diets have gained huge popularity among dog owners in recent years. Supposedly because they are more in line with what a canine’s ancestors (wolves) consume. But haven’t dogs’ digestive systems adapted since they first became domesticated? And, if this is true, wouldn’t feeding them foods they’re no longer used to eating be harmful? Let me be clear: raw diets are a fad, and they may be endangering your pet.
Dogs were domesticated roughly 14,000 years ago.1 This is a fuzzy number because once domesticated, they were actually crossbred back into the ancestral wolf populations many times, over numerous generations. In fact, wolves are still being bred “back” into domestic dog populations today, among some dog sledders (which I don’t discourage, but I’m not sure if I encourage it either) and among wolf-hybrid enthusiasts (something I strongly discourage, but that’s a blog for another day).
The very concept of domestication is a fuzzy one. What does it mean to be domesticated? Does it mean humans control all breeding? But then in a chicken or egg conundrum (pun intended), what does it mean to “control all breeding”? Chickens are domesticated, yet very little is done to control most breeding under non-production or non-show bird scenarios (i.e. the “standard” barnyard). Mallards and mute swans are pretty much domesticated, and are kept as domestic waterfowl under many conditions. So, does being domesticated mean that the animal in question simply cohabitates within human domiciles? This is a relevant question with respect to the subject matter because most purveyors of raw diets suggest that a raw diet is closer to the “natural” evolutionary state of the diet in the dog. But is the dog in its “natural state” still a wolf?
Two important considerations arise: what wolves eat in their natural habitat (the supposed “natural” evolutionary state of the dog), and whether the gut of the domestic dog has evolved to eat food that is different from that of a wolf. In short, has there been enough evolutionary time to allow for dog’s digestive tracts to diverge sufficiently from wolves such that they have different nutritional requirements? The answers are: Wolves eat a wide variety of foods. They are not obligate carnivores. And: Yes, dogs’ digestive tracts are different from wolves’ digestive tracts.
What do Wolves Eat?
Depending upon the ecosystem and the season, a wolf’s diet in the wild is highly variable and includes meat, fruits, vegetables, and even fungi. But mostly meat. In Yellowstone National Park, summer scat analysis revealed an increased variety in diet compared with observed winter diets. Ungulate species (elk, bison, and deer), rodents, and vegetation were all consumed. The highly nutritious organs were consumed first, followed by major muscle tissue, and eventually bone and hide. Wolves in Yellowstone are adapted to a feast-or-famine foraging pattern, and packs typically kill and consume an elk every 2-3 days.
However, wolves in Yellowstone National Park have gone without fresh meat for several weeks by scavenging off old carcasses that consist mostly of bone and hide.2 By comparison, in Alaska, “marine resources may augment the diet of southeast Alaska wolves during seasonal or annual fluctuations in the availability of deer, particularly in those areas on the mainland where densities of terrestrial ungulates are relatively low.”3
In European Russia the diet of wolves mainly consists of carcasses of dogs and wolves, which are left in the forest or used as bait by hunters, resulting in astronomical prevalence rates for some parasites in the wolf populations there.4 So the diet of wolves, and in most canids5 “in the wild” is highly plastic, i.e. it varies widely under varying circumstances. It can include vegetation, fruits, and other food sources besides meat.
The Dietary Evolution of Domesticated Dogs
Has there been enough evolutionary time to allow for doggie digestive tracts to diverge sufficiently from wolves such that they have different nutritional requirements? Yes.
One study found “a significant correlation between genetic distances and dietary differentiation (explaining 46% of the variation) … when geographic distance was accounted for as a co-variable. These results…reinforce earlier studies suggesting that diet and associated habitat choice are influencing the structuring of populations in highly mobile carnivores.”6
In fact, it is widely accepted that “adaptations allowing dogs to thrive on a diet rich in starch, including a significant AMY2B copy number gain, constituted a crucial step in the evolution of the dog from the wolf.” AMY2B copy number gain means increased expression of a gene responsible for increasing production of amylase, a gene called pancreatic α-amylase 2B. Amylase is a digestive enzyme produced in the salivary glands and the pancreas that is responsible for breaking starches down into simple sugars.7
Dog are better at digesting starches than wolves, so this study suggests that such a difference in digestive system genetics is due to domestication. Also, the expression of AMY2B is greater in dog breeds associated with agricultural people, suggesting further that the driving force in increasing the expression of this gene is diet, not geography or random chance. In short, the diet of “domesticated” wolves changed them genetically from wolves into dogs. Not only that, but several other genes associated with digestion of starches and sugars are more readily expressed in the domestic dog than in the wolf.8
In basic terms, a dog’s digestive system is not genetically identical to a wolf’s digestive system. It has been altered by coevolution with human feeding habits, including the development of agriculture. So, feeding your dog a wolf’s diet is not necessarily good for him or her. Doing so might actually deprive your pet of needed nutrients. Which brings us to a second point regarding raw diets.
The Nutritional Value of Raw Diets
Many people say raw diets are better for your pet because pure chicken meat is better for your pet than chicken meal. Here’s the catch: chicken meal is a more complete nutrient-rich source of energy for your pet. Think of it this way: if you were stranded on a desert island, and you had a choice of eating chicken meal or chicken breast, you should choose the chicken meal. The chicken meal includes bones, organs, and fatty tissue that the chicken breast lacks. Though it doesn’t sound particularly appetising, these elements contain a broader array of nutrients meaning you could survive longer and in better health on chicken meal than on chicken meat, all other things being equal.
Raw meat diets may tout raw meat as the main ingredient, but they must balance the raw meat with adequate sources of calcium and phosphorous for your pet. Surviving only on meat can lead to calcium deficiencies and nutritional secondary hyperparathyroidism. This is where the parathyroid glands secrete too much parathyroid hormone in response to chronically low calcium blood levels. As a result calcium and phosphorus leach from the bones in an effort to maintain calcium in the bloodstream, eventually causing skeletal weakness and pathologic fractures. So again, all meat diets for your pet are no good.
“100% complete [nutrition] assumes 100% complete knowledge of food and nutrition, biology, genetics, chemistry and physics. It is a common myth that the minimum and maximum amount of essential nutrients needed for “normal” dogs is known. Most is not known, we are just trying to avoid toxicities and deficiencies.” Dr. Doug Kneuven, DVM Given the many vagaries of dog nutrition, producers usually make their diets carry the AAFCO (Association of American Feed Control Officials) seal stating that the food is “formulated to meet the nutritional levels established by the AAFCO Dog (or cat) Food Nutrient Profiles for adult maintenance.”9
This means the food has been tested or the nutrient levels in the food have been found to meet the levels required by AAFCO. Raw food diets are less likely to have the AAFCO seal. Many raw food proponents argue that making raw foods fit into the same box as dried kibble foods is unfair for several reasons. First, bioavailability may be increased for nutrients such as zinc in raw food. Second, they argue that the AAFCO approval process is biased against raw foods. Also, they argue that many artificially made vitamins and nutrients are added to dog foods because they are literally “cooked out” of the diet as the kibble is produced. Without the AAFCO seal, however, the pet owner cannot verify if the food is complete in its nutrient levels.
Most raw food diets are not abrasive enough on dogs’ teeth to clean off developing tartar. Dogs fed raw diets are therefore more likely to develop dental disease than dogs eating dry kibble. A survey of thousands of dogs and cats seen by veterinarians in Poland identified brushing and the use of dental treats as significant factors reducing the risk of oral disease. No surprise there. However, the results also showed that homemade diets were associated with an increased risk of oral disease and that exclusive feeding of dry diets reduced the risk of oral disease.10 More study in this area is needed, however.
The last strike against raw food diets for your pets is the biggest: raw foods are more likely to contain Salmonella and Listeria bacteria, both of which are food poisoning agents that can kill your pet. It’s that simple. Among scads of other similar studies11-15, the Food and Drug Administration did a two-year study checking for Salmonella and Listeria in different types of dog foods and found overwhelmingly that raw foods had a higher level of both food poisoning agents. The following table is from the FDA website:
Not only is there an increased risk to your pets, but also there is an increased risk to you, as the one who handles and prepares the food for your pet.
Personally, I recommend clients steer clear of Raw Food Diets based on 5 principles:
- First, the desire that Raw Food Diets are more “natural” for your pet is misguided. Your pet’s ancestors are dogs, and they have different nutrient requirements and different genetics than wolves.
- Second, chicken meal is not a bad thing. It includes bones and organ meats which provide a broader array of nutrients than plain chicken breast.
- Third, many Raw Food Diets are not AAFCO approved, so you cannot be certain they provide the completely balanced nutrition your pet needs.
- Fourth, Raw Food Diets may not do as good a job at keeping your pet’s teeth clean as kibbled diets.
- Finally, and most significantly, Raw Food Diets can be a prolific source of food poisoning agents for you and your pet. It is best to steer clear of them and eliminate the increased food poisoning risk due to Salmonella and Listeria pathogens.
Meet the Author
Dr. Kevin Kimber
Dr. Kimber has a Masters in Zoology from Cornell University, graduated from Cornell University College of Veterinary Medicine in 2001. As well as being the Chief Veterinary Medical Officer for Activ4Pets, he is a member of the American Veterinary Medical Association and currently maintains Veterinary licensure in the States of New York and Minnesota, with licensure pending in Florida.
Dr. Kimber possesses over 15 years of veterinary experience practicing Small Animal and Exotic Medicine.
1. Origins of the dog: Domestication and early history. 1995. Cambridge University Press, New York, p. 7-20. In: Serpell J, editor, The domestic dog: Its evolution, behavior and interactions with people. Clutton-Brock J.
2. J Nutr. 2006 Jul;136(7 Suppl):1923S-1926S. Foraging and feeding ecology of the gray wolf (Canis lupus): lessons from Yellowstone National Park, Wyoming, USA. Stahler DR, Smith DW, Guernsey DS.
3. Oecologia. 1999 Aug;120(3):327-335. doi: 10.1007/s004420050866. Assessment of anadromous salmon resources in the diet of the Alexander Archipelago wolf using stable isotope analysis. Szepanski MM, Ben-David M, Van Ballenberghe V.
4. Parasite. 2001 Jun;8(2 Suppl):S88-9. High prevalence of Trichinella nativa infection in wolf (Canis lupus) populations of Tvier and Smoliensk regions of European Russia. Casulli A, La Rosa G, Amati M, Pozio E.
5. Ethol. Ecol. Evol. 1995 7:49-72. Comparative social ecology of feral dogs and wolves. Boitani L, Ciucci P.
6. PLoS One. 2012;7(6):e39341. doi: 10.1371/journal.pone.0039341. Epub 2012 Jun 29. Dietary differentiation and the evolution of population genetic structure in a highly mobile carnivore. Pilot M, Jędrzejewski W, Sidorovich VE, Meier-Augenstein W, Hoelzel AR.
7. Heredity (Edinb). 2016 Nov;117(5):301-306. doi: 10.1038/hdy.2016.48. Epub 2016 Jul 13. Diet adaptation in dog reflects spread of prehistoric agriculture. Arendt M, Cairns KM, Ballard JW, Savolainen P, Axelsson E.
8. PLoS One. 2016 Feb 10;11(2):e0148899. doi: 10.1371/journal.pone.0148899. eCollection 2016. Dietary Variation and Evolution of Gene Copy Number among Dog Breeds. Reiter T, Jagoda E, Capellini TD.
9. J Anim Sci. 2014 Sep;92(9):3781-91. doi: 10.2527/jas.2014-7789. Epub 2014 Jul 8. Natural pet food: a review of natural diets and their impact on canine and feline physiology. Buff PR, Carter RA, Bauer JE, Kersey JH.
10. British Journal of Nutrition (2011), 106: S124-S127.The impact of home-prepared diets and home oral hygiene on oral health in cats and dogs. Buckley C, Colyer A, Skrzywanek M, Jodkowska K, Kurski G, Gawor J, Ceregrzyn M.
11. J Vet Intern Med. 2013;243(11):1549-1558. Current knowledge about the risks and benefits of raw-meat based diets for dogs and cats. Freeman LM, Chandler ML, Hamper BA, Weeth LP.
12. Foodborne Pathog Dis. 2014; 11(9):706-709. Investigation of Listeria, Salmonella, and Toxigenic Escherichia coli in various pet foods. Nemser SM, Doran T, Grabenstein M. et al.
13. J Am Vet Med Assoc. 2006;228(4): 537-542. Evaluation of bacterial and protozoal contamination of commercially available raw meat diets for dogs. Strohmeyer RA, Morley PS, Hyatt DR, Dargatz DA, Scorza AV, Lappin MR.
14. MMWR Morb Mortal Wkly Rep. 2006; 55(25):702-705. Human salmonellosis associated with animal-derived pet treats – United States and Canada, 2005. Centers for Disease Control and Prevention.
15. Clin Infect Dis. 2006; 42(5):686-691. Human health implications of Salmonella-contaminated natural pet treats and raw pet food. Finley R, Reid-Smith R, Weese JS.