Are Dogs Carnivores? An In-Depth Look at the Science
Are Dogs Carnivores?
No – Dogs are classified as omnivores, like you and me.
Those claiming that dogs are carnivores usually begin with the argument that dogs descended from wolves and therefore must be carnivores or at least have a “carnivorous bias.” In this article I will not only address this common misconception, but I will also address the most common arguments made in favor of dogs eating meat and explore the science behind each.
Before diving in, it is important to mention that similar to most wild animals, the diet of a wolf is meant to maintain their health through their reproductive years – that is not very long. For our pets, however, we are not feeding to meet basic needs—we are feeding for health and wellness. It is our goal for our dogs to maintain health well past their reproductive years and live longer than wild wolves.
Dogs Evolved from Wolves
Yes, dogs evolved from wolves, but the key word is evolved – a modern dog is not a wolf (and should not be fed like one). Dogs descended from a population of wolves that are thought to have gone extinct towards the end of the Ice Age (Bergstrom, 2022). The divergence of dogs took place as early as 40,000 years ago, with evidence of the first actual domesticated dogs found in human campsites occurring around 15,000 years ago (Freedman et al, 2014).
So how did dog domestication occur? At that time humans lived in hunter-gatherer societies, and the wolves that were less fearful, ventured closer to humans, eating the food scraps and waste near their human settlements. With a regular food source, these friendlier wolves flourished and had many offspring. They passed on their behavioral characteristics, namely that friendliness, to their offspring. As they evolved, they became smaller and much less aggressive. Other traits that accompanied friendliness included: their teeth became smaller, their snouts shortened, and many developed curly tails and floppy ears.
As humans shifted from hunter-gatherers to ones dominated by agriculture, starch became a larger part of their diet, and in turn, they had to become better at digesting starch, gaining many more copies of the gene responsible for starch digestion. The same occurred in dogs. Since they lived alongside humans, they too began consuming more starch, and duplication of a gene called AMY2B gene, which is responsible for pancreatic amylase production, occurred. Modern day dogs have developed many more copies of these genes making them functionally omnivorous and able to eat and properly digest more starchy foods. The ability of modern dogs to thrive on a diet rich in starch, relative to the carnivorous diet of wolves, constituted a crucial step in the early domestication of dogs.
In 2013, a group of researchers set out to compare the genome of dogs to the genome of wolves in order to further shed light on the genetic changes that accompanied the transformation of ancient wolves into domestic dogs. They found that 36 regions of the genome differ, and were likely found to represent targets for selection during dog domestication. These regions contained genes that fell into two main categories—those genes important in brain function, and likely responsible for behavior traits, and those responsible for starch digestion and fat metabolism (Axelsson et al., 2013).
As we now know, the differences between dogs and wolves do not stop at the AMY2B gene copy number. Humans have coevolved with dogs, and a 2015 study demonstrated that when a human and dog interact, both experience an increase in oxytocin levels (Nagasawa et al, 2015). Further, dogs look to humans for help during tasks, whereas socialized wolves do not (Miklosi et al., 2003).
Dogs Belong to the Order Carnivora
Yes, dogs do belong in the Order Carnivora, but this does not make them carnivores. In fact, Giant Pandas also belong to the Order Carnivora and we know they are strict herbivores. The classification of pandas within the Carnivora order is due to their evolutionary history and certain characteristics they share with other carnivores, such as dental and skeletal features. While giant pandas primarily consume bamboo, they possess a set of carnivore-like teeth with sharp, pointed molars and a single, enlarged wrist bone. Similar to pandas, dogs also share certain characteristics with carnivores, but this does not make them carnivores.
Dogs Are “Optimized for Eating Meat” Because…
Dogs Do Not Produce Salivary Amylase
Many who claim that dogs’ bodies are optimized for eating meat claim that dogs do not produce salivary amylase. Although this was once believed to be true, this is false. According to the Department of Veterinary Internal Medicine at Chungnam National University College of Veterinary Medicine as well as other supporting studies, dogs do in fact produce salivary amylase (Contreras-Agular et al., 2017; Hong et al., 2019)
Dogs Have an Acidic Stomach pH
Typically, carnivorous animals have a more acidic stomach pH – which is believed to be adapted to digest animal proteins and destroy the bacteria present in their prey. For example, a white backed vulture’s (obligate carnivore) gastric pH is 1.2, whereas a cow’s (herbivore) rumen has a pH of around 6-6.5 (Dunn et al., 2020). Many will claim that the stomach pH of a dog is more similar to that of a carnivore, and therefore dogs are “optimized for eating meat.” While stomach pH can correlate with diet, it does not mean an animal “should” or is “optimized” for eating a certain diet.
Let’s take dogs and humans for example. There is a wealth of research suggesting vegan diets for humans are healthier than carnivorous diets, however the pH of a human’s stomach is around 1.1-1.5 (Lui et al., 1986; Dunn et al., 2020). What about a dog? The pH of a dog’s stomach is typically around 4.5 (Dunn et al., 2020). As you can see, humans have a lower gastric pH than dogs, which some would argue means they are more “optimized for eating meat.” However there is a wealth of research supporting vegan diets over carnivorous diets in humans as they lead to better health outcomes (Tuso et al, 2013; Tantamango-Bartley et al., 2016; Willet et al., 2019; Qian et al., 2019). Dogs have a less acidic stomach so it would not be unimaginable to think they are less “optimized” for eating meat than humans.
Dogs Do Not Have Multiple Stomachs
Another common argument is that herbivores have multiple stomachs, which dogs lack. This is entirely untrue. Ruminants are the only herbivores that have multiple stomachs. There are many herbivores (such as the Giant Panda mentioned above) that have a single stomach just like dogs (and wolves for that matter).
Dogs Have Teeth Similar to Carnivores
And lastly, many argue that dogs are closer to carnivores because they have sharp teeth for shearing meat and a temporomandibular joint (TMJ) that primarily moves in an up-and-down motion.
The truth is that dogs have flatter molars than carnivores do. As for their TMJ, their jaw's primary up-and-down motion is not an exclusive indicator of their dietary habits. The jaw movement of dogs is adapted to accommodate a wide range of dietary options, but it may not be as versatile as that of some other omnivores or herbivores. Furthermore, dogs do have some lateral (side-to-side) jaw movement, which enables them to chew, grind, and process various foods. However, the range of lateral motion in dogs is more limited compared to animals with more specialized adaptations for plant-based diets, like herbivores.
What Do the Experts Say?
Ultimately, dogs are omnivores and can adapt to a wide range of diets based on availability and domestication. Their adaptability allows them to consume a diverse array of foods, including meat, vegetables, grains, and commercial dog food.
According to Tufts School of Veterinary Medicine, “From a biological perspective, dogs lack most of the metabolic adaptations to a strict diet of animal flesh that are seen in true carnivores such as cats or ferrets. Compared to true carnivores, dogs not only produce more of the enzymes needed for starch digestion, but they also have much lower protein and amino acid requirements and can more easily utilize vitamin A and D from plant sources, just as people do. All of these factors make them more accurately classified as omnivores rather than carnivores, meaning they can do well on meat or plant-based diets” (Heinze, 2016).
So What Should Dogs Eat?
Whether we want to accept it or not, humans have contributed greatly to the evolution of dogs and what they eat. Ultimately, dogs require six essential nutrients (water, protein, fat, carbohydrates, vitamins, and minerals) and it does not matter whether they are receiving those nutrients from plant or animal sources. Yeast, for example, contains more protein by weight than beef, is incredibly sustainable, and has been found to be an appropriate protein source for dogs as it contains all the essential amino acids dogs require (Reilly et al., 2021).
As a reminder, do not believe everything you read. There is much misinformation on the internet and it is important to think critically about the information being presented and make sure to check the references.
References
Axelsson E. et al, The genomic signature of dog domestication reveals adaptation to a starch-rich diet, Nature, 2013 Jan 23, doi: 10.1038/nature11837, Science for Life Laboratory, Department of Medical Biochemistry and Microbiology, Uppsala University, 75237 Uppsala, Sweden
Barbiers, R. 1990. Natural history and captive management of maned wolves. Proc. Am. Ass. Zoo. Vet., pp. 58-60.
Barboza, P. S., Allen, M. E., Rodden, M. and Pojeta, K. 1994. Feed intake and digestion in the maned wolf (Chrysocyon brachyurus): consequences for dietary management. Zoo Biology, 13, 375–381.
Bergström, A., Stanton, D.W.G., Taron, U.H. et al. Grey wolf genomic history reveals a dual ancestry of dogs. Nature607, 313–320 (2022). https://doi.org/10.1038/s41586-022-04824-9
Contreras-Aguilar, M.D., Tecles, F., Martínez-Subiela, S. et al. Detection and measurement of alpha-amylase in canine saliva and changes after an experimentally induced sympathetic activation. BMC Vet Res 13, 266 (2017). https://doi.org/10.1186/s12917-017-1191-4
Dunn Robert R., Amato Katherine R., Archie Elizabeth A., Arandjelovic Mimi, Crittenden Alyssa N., Nichols Lauren M., The Internal, External and Extended Microbiomes of Hominins, Frontiers in Ecology and Evolution, Volume 8, 2020,
Freedman AH, Gronau I, Schweizer RM, Ortega-Del Vecchyo D, Han E, Silva PM, Galaverni M, Fan Z, Marx P, Lorente-Galdos B, Beale H, Ramirez O, Hormozdiari F, Alkan C, Vilà C, Squire K, Geffen E, Kusak J, Boyko AR, Parker HG, Lee C, Tadigotla V, Wilton A, Siepel A, Bustamante CD, Harkins TT, Nelson SF, Ostrander EA, Marques-Bonet T, Wayne RK, Novembre J. Genome sequencing highlights the dynamic early history of dogs. PLoS Genet. 2014 Jan;10(1):e1004016. doi: 10.1371/journal.pgen.1004016. Epub 2014 Jan 16. Erratum in: PLoS Genet. 2014 Aug;10(8):e1004631. Wilton, Alan
Heinze CR, VeganDogs—A healthy lifestyle or going against nature?, Tufts Clinical Nutrition Service Petfoodology, 2016.
Hong HR et al. Salivary alpha-amylase as a stress biomarker in diseased dogs. J Vet Sci. 2019 Sep;20(5):e46 https://doi.org/10.4142/jvs.2019.20.e46 pISSN 1229-845X·eISSN 1976-555X
Lui CY, Amidon GL, Berardi RR, Fleisher D, Youngberg C, Dressman JB, Comparison of Gastrointestinal pH in Dogs and Humans: Implications on the Use of the Beagle Dog as a Model for Oral Absorption in Humans, Journal of Pharmaceutical Sciences, Volume 75, Issue 3, 1986, Pages 271-274, ISSN 0022-3549, https://doi.org/10.1002/jps.2600750313.
Miklósi A, Kubinyi E, Topál J, Gácsi M, Virányi Z, Csányi V. A simple reason for a big difference: wolves do not look back at humans, but dogs do. Curr Biol. 2003 Apr 29;13(9):763-6. doi: 10.1016/s0960-9822(03)00263-x. PMID: 12725735.
Nagasawa M, Mitsui S, En S, Ohtani N, Ohta M, Sakuma Y, Onaka T, Mogi K, Kikusui T. Social evolution. Oxytocin-gaze positive loop and the coevolution of human-dog bonds. Science. 2015 Apr 17;348(6232):333-6. doi: 10.1126/science.1261022. Epub 2015 Apr 16. PMID: 25883356.
Phipps A, Edwards M. 2009. Diets offered to maned wolves (Chrysocyon brachyurus) in North American zoos: a review and analysis. In Ward A, Treiber K, Schmidt D, Coslik A, Maslanka M, Eds. Proceedings of the Eighth Conference on Zoo and Wildlife Nutrition, AZA Nutrition Advisory Group, Tulsa, OK.
Qian F, Liu G, Hu FB, Bhupathiraju SN, Sun Q. Association Between Plant-Based Dietary Patterns and Risk of Type 2 Diabetes: A Systematic Review and Meta-analysis. JAMA Intern Med. 2019 Oct 1;179(10):1335-1344. doi: 10.1001/jamainternmed.2019.2195. PMID: 31329220; PMCID: PMC6646993.
Reilly LM, He F, Rodriguez-Zas SL, Southey BR, Hoke JM, Davenport GM, de Godoy MRC. Use of Legumes and Yeast as Novel Dietary Protein Sources in Extruded Canine Diets. Front Vet Sci. 2021 Jun 4;8:667642. doi: 10.3389/fvets.2021.667642. PMID: 34150888; PMCID: PMC8212060.
Tantamango-Bartley Y, Knutsen SF, Knutsen R, Jacobsen BK, Fan J, Beeson WL, Sabate J, Hadley D, Jaceldo-Siegl K, Penniecook J, Herring P, Butler T, Bennett H, Fraser G. Are strict vegetarians protected against prostate cancer? Am J Clin Nutr. 2016 Jan;103(1):153-60. doi: 10.3945/ajcn.114.106450. Epub 2015 Nov 11. PMID: 26561618; PMCID: PMC4691666.
Tuso PJ, Ismail MH, Ha BP, Bartolotto C. Nutritional update for physicians: plant-based diets. Perm J. 2013 Spring;17(2):61-6. doi: 10.7812/TPP/12-085. PMID: 23704846; PMCID: PMC3662288.
Willett W, Rockström J, Loken B, Springmann M, Lang T, Vermeulen S, Garnett T, Tilman D, DeClerck F, Wood A, Jonell M, Clark M, Gordon LJ, Fanzo J, Hawkes C, Zurayk R, Rivera JA, De Vries W, Sibanda LM, Afshin A, Chaudhary A, Herrero M, Agustina R, Branca F, Lartey A, Fan S, Crona B, Fox E, Bignet V, Troell M, Lindahl T, Singh S, Cornell SE, Reddy KS, Narain S, Nishtar S, Murray CJL, Food in the Anthropocene: the EAT–Lancet Commission on healthy diets from sustainable food systems, The Lancet, Volume 393, Issue 10170, 2019, Pages 447-492, ISSN 0140-6736, https://doi.org/10.1016/S0140-6736(18)31788-4.
