Plants are an essential part of any diet but can dogs be sustained on plants alone? Veganism is not only a diet but a lifestyle for many humans. It is a rapidly growing trend, with many people making the switch for various reasons including sustainability, animal ethics and health. One survey even suggested that there was a 40% increase in veganism in 2020 alone. With more and more people making the switch to a plant based diet, many pet owners are wondering if their furry family members can also make the transition with them.
Many pet owners think that because dogs descend from wolves they are true carnivores as well. However, while dogs still share some similar characteristics to wolves, they have been domesticated for over 15,000 years and have evolved during that time. This includes fundamental changes in their DNA and digestive physiology.
Dogs are classified under the order Carnivora. While that may sound like it closes the question on dogs being carnivores, there are actually quite a few omnivorous species in this category, including bears, racoons, and skunks.
Through selective breeding, dog morphology and physiology has greatly evolved. Probably the most notable change is to body size. Wolves are large creatures, designed to take down equally large prey. An animal the size of a wolf would have been a lot more difficult for humans to control during early domestication. As a result, the dog was selectively bred to be smaller and more manageable for feeding and training. This takes away some of its ability to hunt large prey like wolves do.
Arguably the most important difference between wolf and dog nutrition is gastrointestinal morphology. Dogs have evolved to eat what humans eat and this means that the dog’s GI system has also evolved. Dogs are more genetically equipped to digest starches and produce longer chain starch-digesting enzymes than wolves do. This means that it is easier for dogs to break down and absorb starch sources like potatoes, rice and peas.
Ultimately, dogs are not considered true carnivores but they are not true omnivores either. This means that while dogs do need meat to survive, they can also benefit from plants in their diet as well. Since dogs can digest carbohydrates, they can benefit from the energy, vitamins and minerals that plants contain.
As a trained companion animal nutritionist, I am always searching for new ways to improve dog health through food. Unfortunately, a true vegan diet may not be the answer. While dogs eat a lot of the same foods that us humans do, they digest and absorb nutrients in a slightly different manner. As a result, a full plant based diet is not completely sustainable for them. A diet completely devoid of meat, could cause dogs to become malnourished and impair normal growth and other body functions. From a nutritionist point of view, I would not recommend that owners feed their dogs a vegan diet, homemade or commercial, without consulting their veterinarian.
One of the reasons that vegan diets are sustainable for humans is that we can replace a lot of the protein and fat from meat products with plant products like nuts, seeds, fungi, soy, and legumes. Dogs require a lot more protein and fat in their diet than humans do. According to the Association of American Feed Control Officials (AAFCO), adult dogs require a minimum of 18% crude protein and 5.5% crude fat in their diet. While it is difficult to formulate a dog diet to meet these minimums with only plant products, it is possible. However, where the problem arises is the degree of digestibility of the ingredients used.
Two very important terms in nutrition are digestibility and bioavailability. Digestibility is the proportion of ingested food that is broken down in the digestive tract and absorbed into the body. Meanwhile, bioavailability is the degree to which a specific ingested nutrient is absorbed into the body.
Different ingredients have different levels of digestibility. When it comes to protein ingredients, you want a source that is highly digestible to dogs. This means that a higher proportion of the protein will be utilized for growth and maintenance. Plant protein ingredients like soy and legumes are high in protein, however dogs cannot fully digest these products to the degree that they need to to be able to fully absorb the protein. Proteins from animal sources such as muscle and organ tissue are typically more digestible than those from plant or insect sources, regardless of their overall protein content.
A 2009 study by researchers at Bednar et al. examined the digestibility of a soybean meal diet compared to poultry meal in dogs. The goal of the study was to determine if soybean meal, a common plant protein ingredient, was digestible enough to replace animal meat in canine diets. Results of the study showed that the poultry meal diet was significantly higher in mean crude protein digestibility in ileal cannulated dogs, compared to the soybean meal diet. Dogs fed the soybean meal diet also had a much higher fecal output compared to the other diets, indicating a low total tract digestibility due to high indigestible fibre.
To remedy the low protein digestibility of plant ingredients, many vegan dog food manufacturers will use highly processed ingredients, such as pea protein meal, soy protein concentrate and fermented plant proteins to improve the digestibility of nutrients in these ingredients. This means that these ingredients are processed in a way that separates the protein from the other nutrients in the plant product. During this process, many of the nutrients, like amino acids and vitamins, that were originally contained within the ingredient may be destroyed. Dog food should include as many whole foods as possible and with vegan dog diets, this is not plausible.
This means that while vegan diets can be formulated on paper to meet the minimum protein and fat requirements for dogs, they are not digestible enough for them to fully absorb all of the essential nutrients they need to be healthy. Compared to humans, dogs unfortunately cannot digest plant products as efficiently as we can. This is why even though humans can easily sustain a plant based diet, dogs cannot.
While some dogs will readily eat anything and everything, there are just as many that are picky eaters. Palatability is the measure of intake of a food that indicates acceptance or the measure of preference of one food over another- essentially the measure of which food tastes the best to dogs. Protein and fat are the most palatable nutrients to dogs and without the protein and fat from animal products in their food, some dogs may be less inclined to eat their whole meal. There is already a risk of nutritional deficiency when it comes to vegan diets. If a dog does not eat their whole meal, the risk of deficiency increases exponentially. As a result, the low palatability of plant based diets could put picky eaters at risk of becoming malnourished.
The unfortunate news for vegan pet owners is that there is a major lack of evidence supporting vegan diets for dogs. This is not to say that there are no studies on vegan dog diets at all. Following the trend of veganism in human nutrition, there have been a few clinical and survey based studies completed to determine the viability of vegan diet for dogs. The results of these studies are mixed and there is a lot of evidence showing that commercial vegan diets present a lot of deficiencies in essential nutrients.
For example, one 2020 study evaluated the macronutrients composition, fatty acid and amino acid profiles, and essential minerals content of vegan foods for dogs and cats available on the market. The goal of the study was to compare these essential nutrient results with European Pet Food Industry Federation (FEDIAF) and AAFCO nutrient recommendations. It was concluded that all foods analyzed had one or more nutrients below the recommended levels and some presented zinc and copper in excess. Therefore, the dietary deficiencies found in these foods may lead to health risks.
Another 2015 study examined protein and amino acid concentrations of commercial vegetarian diets formulated for dogs. It was found that most diets assessed in the study were not compliant with AAFCO labeling regulations, with only 8 of the 27 diets being compliant with all pet food label regulations established by the AAFCO. Furthermore, of the 23 diets examined, 6 diets did not meet all amino acid minimums, compared with the AAFCO nutrient profiles. This is a very critical finding as amino acids are the essential building blocks that make up protein.
There is limited research when it comes to long term feeding of vegan diets for dogs. Hopefully more research can be conducted to support the use of plant based diets for dogs. However at this time the current research shows that relying on a true vegan diet for your dog may be risky.
Vegan diets may not be the answer for our pups but there are other plant forward alternatives out there to consider. A few options include vegetarian diets, meatless meals and vegan treats. These types of dog foods ensure that your dog is receiving the proper nutrition they need to grow and thrive while still minimizing the amount of meat and animal products they consume.
Vegetarian diets put plants first, while still maintaining all of the protein and essential nutrients that dogs need. Rather than relying on animal meat, vegetarian diets prioritize using plant proteins and also supplement with minor animal products like eggs, cottage cheese, whey protein and insect protein. These diets rank much higher in total protein digestibility than vegan diets, while still being conscious of sustainability and animal ethics.
There are many of us humans who agree with a lot of the values of eating plant based but we just can’t bring ourselves to give up that juicy steak or scrumptious chicken breast. This is where meatless meals are a great idea! Dedicate one day a week for you and your dog to eat plant based. Vegan diets may not be sustainable for dogs long term but a vegan meal once or twice per week won’t hurt them!
What dog doesn’t love a good treat? The good news is that there are many vegan treats on the market and there are even recipes for you to make your dog vegan treats at home. Since treats are meant for supplemental feeding and aren’t to be relied on for a whole meal, there is no risk of nutrient deficiency! Check out our recipe for our 4 ingredient vegan dog biscuits!
Even though dogs cannot sustain life on plants alone, plant products still provide dogs with a lot of great health benefits. A canine diet that is supplemented with carbohydrates, fruits and veggies makes for the perfect balance in a canine diet. Plants are a source of many essential nutrients including vitamins, minerals, carbohydrates, fibre, fats and proteins. Different plants have different levels of nutrients and balanced together can be a healthy addition to any canine diet.
The primary source of nutrients dogs receive from plants are carbohydrates, which are broken down into 2 main categories; soluble (starch) and insoluble (fibre). Starches are easily digested and broken down in the digestive tract and converted into energy by the liver. This energy is used by dogs for doing dog things like running and playing. Fibre is a carbohydrate with a different function. Fibre is more slowly degraded in the digestive system and sometimes isn’t absorbed at all. That doesn’t mean it doesn’t have a function though! Since fibre is slowly digested, it sits in the gastrointestinal tract for longer. This is a good thing as it helps to keep dogs full throughout the day. Fibre also aids digestion as it is utilized by beneficial bacteria in the intestines. The bacteria use fibre to help digest other nutrients in the dog’s food. Furthermore, fibre also acts as “nature’s broom”. Fibre helps to sweep food down the digestive tract, making for better, more consistent poops.
Just a general reminder that too much of something is never good. In high amounts, starch can raise blood sugar, putting dogs at risk for diabetes. It is usually recommended to feed dogs slowly digestible starches like brown rice, peas and lentils rather than ingredients high in available starch like corn or wheat. Conversely, if there is too much fibre in a dog’s food, it replaces the digestible nutrients and becomes just a “filler”.
Certain plant products are also a great source of polyunsaturated fats- the good fats that help to lower cholesterol! Sources of these fats include ingredients like chia seeds, hemp hearts and flax seeds, which are all high in omega 3 fatty acids.
Many plant products like fruits and veggies and certain herbs and spices are also good sources of antioxidants. While antioxidants are beneficial in reducing inflammation, they are best utilized as a preventative measure. This is because antioxidants reduce and repair the damage inflicted by free radicals before a severe inflammatory reaction even occurs. Not to mention, antioxidants can also help fight diseases like cancer, diabetes and pancreatitis! Some foods that are high in antioxidants are:
Exercise caution if you’re considering feeding a vegan diet to your dog. Both commercial and homemade vegan dog diets have low digestibility when it comes to certain essential nutrients. This could result in deficiencies and your dog becoming malnourished. Instead consider plant forward alternatives such as vegetarian diets, meatless meals and vegan treats to keep your pup happy and healthy. There are many health benefits to feeding your dogs plant products, so consider supplementing your dog’s regular food with some healthy fruits and veggies. Hopefully with more research we can find a vegan solution for dogs.
The Guardian. “From fringe to mainstream: how millions got a taste for going vegan” (2021). https://www.theguardian.com/lifeandstyle/2021/oct/10/from-fringe-to-mainstream-how-millions-got-a-taste-for-going-vegan#:~:text=The%20exact%20numbers%20of%20vegans,part%20of%20this%20year's%20Veganuary.
G. E. Bednar, S. M. Murray, A. R. Patil, E. A. Flickinger, N. R. Merchen & G. C. Fahey Jr. (2000) Selected animal and plant protein sources affect nutrient digestibility and fecal characteristics of ileally cannulated dogs, Archiv für Tierernaehrung, 53:2, 127-140, DOI: 10.1080/17450390009381942
Cummings Veterinary Medical Center “Vegan Dogs – A healthy lifestyle or going against nature?” (2016). https://vetnutrition.tufts.edu/2016/07/vegan-dogs-a-healthy-lifestyle-or-going-against-nature/
Zafalon RVA, Risolia LW, Vendramini THA, Ayres Rodrigues RB, Pedrinelli V, Teixeira FA, et al. (2020) Nutritional inadequacies in commercial vegan foods for dogs and cats. PLoS ONE 15(1): e0227046. https://doi.org/10.1371/journal.pone.0227046
Kanakubo, Kayo, Andrea J. Fascetti, and Jennifer A. Larsen. "Assessment of protein and amino acid concentrations and labeling adequacy of commercial vegetarian diets formulated for dogs and cats." Journal of the American Veterinary Medical Association 247, no. 4 (2015): 385-392.
