Plant-Based Diets For Dogs: Benefits & Drawbacks
We served you the scoop on raw meat based diets and meat-based kibble diets in our article Meat-Based Diets: The Good & The Bad, and now we want to give you all the information on plant-based diets.
Before we jump in let’s tackle the top five myths about plant-based diets.
Top 5 Myths Surrounding Plant-Based Diets for Dogs
Myth #1: Dogs are carnivores
While dogs do belong to the Order Carnivora, they are not classified as carnivores. Fun fact: Pandas also belong to the Order Carnivora—and we certainly know that pandas only eat plants.
Dogs diverged from wolves over 15,000 years ago (that’s a long time ago!), and evolved alongside humans, eating their scraps which included grains, fruits, and vegetables. During domestication, dogs gained many copies of the gene responsible for starch digestion, just as humans did during the agricultural revolution. This makes dogs more accurately classified as omnivores rather than carnivores. What does this mean? Dogs can obtain nutrients from both plant and animal matter, and therefore they can thrive on a plant-based or meat-based diet.
Myth #2: Dogs need protein from meat
Dogs don’t need to eat meat, but they do need high quality protein. And you know what’s loaded with protein? Plants and fungi. The truth is, that the digestive system of a dog doesn’t care where the protein comes from — it matters that the protein is high quality – meaning it is complete, highly digestible, and bioavailable. We need to see beyond the misinformation that puts meat on a pedestal as the only appropriate source of protein.
Protein-rich plant-based ingredients, such as yeast, have been shown to be appropriate protein sources for dogs, and reportedly have digestibility similar to animal-derived ingredients (Dodd et al., 2018; Reilly, 2021; Clapper et al. 2001). The reality is that there are many high quality non-animal sources of protein—one great example is dried yeast. In fact, dried yeast contains 49% protein by weight compared to 24% in beef. It’s also incredibly sustainable as yeast can grow in just 3 days, and requires far fewer resources to produce than any animal-based protein.
Myth #3: Plant-based diets are higher in carbohydrates and lower in protein than meat-based kibble diets
Plant-based isn’t synonymous with carbohydrates as we may think, as protein not only comes from meat, but also comes from plants and fungi. In fact, most commercial dry dog foods typically contain a high proportion of plant ingredients, as a high grain content is necessary for successful extrusion. It is only a small step from some of the popular meat-based dry dog foods to one that contains no meat at all.
The reality is that a commercially produced plant-based kibble can have less carbohydrates and more protein than a meat-based kibble diet. In order to illustrate this point, I compared three plant-based kibble dog foods to five popular and/or veterinarian-recommended meat-based kibble dog foods. I made sure to include a prescription hydrolyzed protein diet commonly prescribed for food-allergic dogs. Wild Earth Performance Formula dog food contains more protein and less carbohydrates than many of the leading vet-recommended dog food brands as shown below on a dry matter basis.
Myth #4: A plant-based diet cannot be as nutritionally sound or as palatable as a meat-based diet
Plant-based diets for dogs can be nutritionally complete and balanced, they just need to be carefully formulated. If formulated correctly, they can not only meet but exceed AAFCO nutritional guidelines. Currently, we evaluate meat-based diets based upon whether they meet these guidelines, and the same method should be used to evaluate plant-based diets.
A 2021 study examined the steps taken to ensure the nutritional soundness and quality of plant-based pet foods and found that plant-based diets were produced at equal or superior standards to meat-based diets, with acceptable or superior standards overall at all stages of formulation (Knight & Light, 2021). Not only can commercially available plant-based diets be of high quality and be healthy, but they can also be delicious and satisfying to dogs. In 2021, a group of researchers from the University of Winchester surveyed the owners of 2,308 dogs (and 1,135 cats), and found that those who were fed plant-based diets for at least one year were just as eager to eat and just as healthy as those fed meat-based diets (Knight & Satchell, 2021).
A plant-based diet for dogs can be balanced and nutritious, help dogs live healthier and longer lives, and be a diet that dogs love! This is not to say that all plant-based diets are created equal, and careful evaluation of the diet must be completed.
Myth #5: A dog’s health will decline on a plant-based diet
More studies are being published that show plant-based food can be healthier for some dogs than conventional diets, and promote longevity. The most recent, comprehensive, and first long-term study was published in 2023. Fifteen clinically healthy client-owned dogs were fed a complete and balanced plant-based diet for a year, and the authors concluded that health was maintained (Linde et al., 2023).
Prior to this groundbreaking study, the authors of a short-term study published in 2021 came to a similar conclusion. Researchers evaluated the short-term amino acid, clinicopathologic, and echocardiographic findings in thirty healthy dogs fed a commercial plant-based diet for 12 weeks, and concluded that the health of the dogs was maintained and did not deteriorate (Cavanaugh et al., 2021). Another study, where sprint-racing sled dogs were fed a nutritionally complete and balanced vegan diet, demonstrated that a carefully balanced meat-free diet can maintain normal hematological values in exercising dogs (Brown et al, 2009).
Now that you know that dogs can thrive on a plant-based diet, and that a plant-based kibble can have more protein and less carbohydrates than meat-based kibble, let’s dive into the potential benefits and drawbacks of feeding a plant-based diet.
Plant-Based Diets: Potential Benefits
Free of Common Food Allergens
The most common culprits involved in cutaneous adverse food reactions in dogs are beef, dairy, chicken, wheat and lamb (Mueller et al, 2016). Plant-based diets are inherently devoid of the majority of these animal-based ingredients, and therefore often offer symptom relief to those dogs with food allergies. In fact, Wild Earth dog food is devoid of all of these allergens, including wheat so it is a great option for food allergic dogs.
Improved Longevity and Fewer Health Disorders
In 2022 alone, three new survey studies were published—all which suggest that a plant-based diet may be healthier for some dogs than conventional diets and promote longevity for our best friends. The first of these, an owner survey, found that dogs who were fed plant-based diets “reported fewer health disorders, specifically with respect to ocular, gastrointestinal and hepatic disorders” (Dodd et al., 2022). Dog longevity was also reported to be greater for dogs fed plant-based diets, with purely plant-based dogs reportedly living 1.5 years longer than dogs fed meat.
Potential Health Benefits and Less Vet Visits
The second of these studies evaluated the health perceptions of 100 pet guardians who fed their dog a plant-based diet, and found that dogs who were fed plant-based dog food found the food palatable, with no adverse changes in appetite or weight (Davies, 2022). Health improvements after 3–12 months were also reported in coat glossiness, dandruff, skin inflammation, itchiness, external ear canal crusting, fecal consistency, defecation frequency, flatus frequency, flatus antisocial smell, anxiety, aggressive behavior, and stool consumption.
Lastly, the third of these peer-reviewed studies included over 2,500 dogs, and revealed that dogs who eat a well-balanced plant-based diet require less medication, visit the vet less frequently, and suffer from fewer health disorders according to their owners when compared to dogs who eat conventional meat-based kibble diets—suggesting that a plant-based diet may be healthier for some dogs (Knight et al., 2022).
Several of these studies were also included in a literature review published in 2023 that analyzed the health impacts of a plant-based diet in cats and dogs. The authors concluded that there is no overwhelming evidence of adverse effects resulting from the feeding of plant-based diets to dogs (or cats), and that there is evidence of benefits (Domínguez-Oliva et al., 2023). Because many of these studies were either short in duration and/or based on the opinions of owners, there exists a need for future high-quality, randomized, controlled studies, with standardized outcome measures, large sample sizes, and longer duration.
With this need identified, a group of clinician-scientists from Western University of Health Sciences’ College of Veterinary Medicine conducted the first comprehensive study on the long-term effects of plant-based diets for dogs. Fifteen clinically healthy client-owned dogs were fed a complete and balanced plant-based diet for a year (Linde et al., 2023). Clinical, hematological, and nutritional parameters were evaluated at 0, 6 and 12 months, including complete blood count, serum chemistry, cardiac biomarkers, plasma amino acids, and serum vitamin concentrations. Comparative analysis of blood work and urinalysis showed no clinically significant changes between baseline, intermediate, and endpoint values. Furthermore, bloodwork values (CBC and blood chemistry) remained within normal reference ranges throughout the study.
A common misconception regarding plant-based diets is that they provide less protein than traditional meat-based diets (which we know is untrue). The researchers further busted this myth by measuring the levels of essential amino acids—all of which were within or above normal reference ranges, with an upward trend. L-taurine and L-carnitine levels were also measured, and an increase in these nutrients was also observed when comparing baseline to endpoint values.
As mentioned, concentrations of vitamins were also evaluated. A very in- teresting and positive finding was seen with vitamin D. Seven dogs presented with vitamin D insufficiency as a result of eating a meat-based diet prior to the start of the study, and after six months of eating a plant-based diet, only one dog was insufficient—and by 12 months all dogs had normal vitamin D levels.
As for vitamin A, concentrations stayed within the reference range and exhibited an upward trend. Vitamin E levels were more than adequate throughout. Lastly, as for B vitamins, folate was below the reference range in six dogs at the outset of the study and by 12 months only three of those dogs had low folate. Cobalamin was within the normal reference interval at all three time points.
In order to evaluate heart health, cardiac biomarkers Cardiac troponin I (cTnI) and NT-proBNP were measured at the three time points, and not only did they maintain within reference ranges, but there was a downward trend in both. Furthermore, cTnI levels were increased in three dogs at baseline, compared to only one dog at endpoint.
Also interesting to note, the body weight of the dogs remained stable, while body condition scores trended downwards in overweight/obese dogs. Plant-based diets have long been correlated with a healthy body weight and this data serves to further support that. As we know, dogs at a normal body weight live on average two to two-and-a-half years longer than overweight/ obese dogs (Salt et al., 2019).
Given the results, the authors concluded that health was maintained after 12 months of being fed a commercial plant-based diet.
Free from animal products and by-products
Traditional meat-based kibble typically contains the parts of animals that may be unfit for human consumption, ranging from organs to those animals that are down, dead, dying, and diseased (4D). While the use of “byproducts,” the non-rendered parts of the animal other than the meat, is environmentally responsible, it adds a question mark to what is actually in the food. Essentially it is often used as a method to keep protein levels high (but not always high quality), and food production costs low. The more problematic meat ingredients are those designated as “meal,” which are the result of rendering. Rendering is defined as “an industrial process of extraction by melting that converts waste animal tissue into usable materials.” In other words, it is a process by which animal parts that are often unfit for human consumption (including expired meats, the 4D meats, and even animals who have drowned after a flood) are chopped up and boiled into a stew which is then dehydrated. The fat and protein portions are then removed and used as animal fat or ground up into “meal,” respectively. To further compound the problem, if the general term “meat meal” is used, the animal the parts came from is not disclosed. Even if a specific animal is named on the label such as “chicken,” for example, meat is often mislabeled, meaning what is on the bag isn’t necessarily what is inside. In 2015, a Chapman University research team looked at 52 commercial pet foods, and found that 40% of those tested contained mislabeled meat products (Okuma et al., 2015).
To add to concerns surrounding meat-based dog food, meat is much more likely to become contaminated with bacteria such as Salmonella. There have been over 180 dog food recalls since 2009, and major ones from bacterial contaminants from meat sources. In fact, 49% of all pet food recalls in the past ten years have been from pathogenic bacteria. The second leading cause of pet food recalls is pentobarbital, a euthanasia drug. In 2018, the director of FDA Center for Veterinary Medicine addressed this, stating “we have reason to believe rendered products can be a source for pentobarbital” (FDA.gov, 2018).
Further, meat-based pet food has not only been found to contain pentobarbital, but it has also been found to contain hormones, antibiotics, and toxic amounts of heavy metals. The Clean Label Project, a national nonprofit focused on health and transparency in labeling, tested the top pet foods and found lead in some pet foods at 16 times the concentration of lead in Flint, Michigan’s tainted drinking water. They also found arsenic in concentrations of 555 times higher than the maximum contaminant level for human drinking water set by the Environmental Protection Agency.
Farm Animal Welfare
Not only are plant-based diets able to meet the nutritional needs of dogs, are associated with fewer health disorders and increased longevity, but they also address concerns regarding farm animal welfare and environmental sustainability. Factory farming is not only cruel, but also brings with it environmental impacts and human health risks. Farm animals are raised in unimaginably horrible conditions and are subjected to suffering their entire lives. They are confined, abused, and treated in the worst ways possible. And to add to that, historically, pet food was typically produced with those animals and the parts of animals that were unfit for human consumption, but now with fresh food and human-grade dog food becoming more popular, more farm animals are raised and slaughtered to meet this demand.
Sustainability
Aside from animal welfare concerns, this has a huge impact on our planet. According to a University of California Los Angeles (UCLA) study published in 2017, meat used for pet food accounts for 25–30% of meat consumed in the United States (Okin, 2017). This roughly creates about 64 million metric tons of greenhouse gas emissions per year, which is equivalent to the annual exhaust produced by 14 million cars. These numbers will only increase as the number of pets increases and more “human-grade” meat products (with actual regulation) hit the market. If dogs and cats in the United States were their own nation, they would rank 5th in meat consumption (Okin, 2017).
Plant-Based Diets: Potential Drawbacks
Historically Have Not Been Complete and Balanced
Veterinarians have rightfully been very skeptical of alternative diets, including plant-based diets for dogs, because many past studies found that historically these were nutritionally deficient. The reason for this was that most people were formulating their own plant-based diets at home, and these, of course, were not nutritionally complete and balanced. In the last several years, however, there has been an explosion in evidence-based research that supports plant-based feeding of dogs, and now we have many commercial companies manufacturing these foods on an industrial level, and most of them are taking good steps to ensure that products meet a high standard and are nutritionally complete and balanced.
Concerns Surrounding Nutrients
When it comes to plant-based diets, essential amino acids and nutrients that are traditionally derived from animal sources are of greatest concern. These include the sulfur-containing AAs methionine, cysteine, and taurine; the omega-3 polyunsaturated fatty acid DHA; and vitamins A, B12, and D.
Let’s begin with taurine and its precursors—sulfur-containing essential amino acids methionine and cysteine. Taurine, although not an essential amino acid, may be conditionally essential particularly for breeds susceptible to taurine-deficient conditions. In dogs, taurine is conjugated with bile acids, leading to high losses through feces. Diets high in fermentable fiber, such as plant-based diets, may exacerbate this loss as they may result in increased bile acid excretion and microbial degradation of these taurine-conjugated bile acids. When evaluating a plant-based diet, it is crucial to ensure that both taurine precursors (sulfur containing amino acids) and taurine are added. “Non-animal sources of these nutrients are readily available, their bioavailabilities have been determined, and they are already used by animal feed industries.” (Dodd et al., 2018).
Now moving on to DHA. DHA, while not considered essential for adult non-reproductive dogs, is essential for gestation, lactation and growth. Contrary to popular belief, DHA is not only concentrated in fish oil, but is also concentrated in marine plant products, such as algae. Therefore, plant-based foods can be formulated to meet DHA requirements (Dodd et al., 2018).
As for vitamins, non-animal sources of most vitamins exist, however vitamins A, B12 and D are primarily sourced from animals. While vitamin A (retinol) is found exclusively in animal tissues, dogs, unlike cats, can utilize the precursor provitamin A carotenoids to form active vitamin A. Provitamin A carotenoids are found in many plants that can be used to formulate canine diets. Examples include vegetables rich in beta-carotene, such as pumpkin and sweet potatoes. Additionally, synthetic vitamin A analogs can also be utilized when formulating plant-based canine diets (Dodd et al., 2018).
Next, let’s discuss vitamin B12, also known as cobalamin. Although cobalamin is produced by microbes in a dog’s gastrointestinal tract, it is produced caudal to the site of absorption—therefore dogs need cobalamin from their diet. Historically, cobalamin has been sourced from animal tissues for use in dog food, however now a bioavailable synthetic version of cobalamin (produced from microbial fermentation) exists—and it is used in both plant-based and meat-based pet foods. The addition of synthetic cobalamin to plant-based diets therefore fulfills the dietary requirement for dogs (Dodd et al., 2018).
Lastly, although most animals can synthesize vitamin D in their skin with adequate UV or sunlight exposure, dogs have a strict dietary requirement for vitamin D because they have high enzymatic catabolism of vitamin D precursors. Dietary sources of vitamin D include vitamin D2 (ergocalciferol) and vitamin D3 (cholecalciferol). Vitamin D3 is more active in most animals, includ- ing humans, however dogs may be able to use both efficiently. Vitamin D2 is plentiful in fungi and yeast. While vitamin D3 has traditionally been derived from sheep lanolin or fish oils, it has also been isolated from plants, such as microalgae, and it is bioavailable. Additionally, commercial preparations of plant-sourced vitamin D3 exist. Therefore, it is entirely possible for a plant- based diet to meet the vitamin D requirement of dogs. If there is concern re- garding the vitamin D status of a dog fed a plant-based diet, veterinarians can monitor serum calcidiol concentrations (Dodd et al., 2018).
All in all, when formulating plant-based diets, special care must be taken to ensure that all nutrient requirements are met, especially requirements for methionine, taurine, DHA, vitamins A, B12 and D which have historically been sourced from animals. As explored, plant-based or synthetic versions of these exist, and therefore plant-based diets can be formulated to be nutritionally complete and balanced.
The Best Decision for Your Dog
So there you have it– the lowdown on plant-based diets for dogs. While helping to save the environment and protecting countless animals from suffering and slaughter certainly have merit, canine health is at the forefront when determining what to feed our dogs. I hope that by now you have come to see that a plant-based diet can be nutritionally complete and balanced given it is carefully formulated, digestible, and bioavailable. By no means am I suggesting that all plant-based diets are nutritionally sound, and therefore I urge you as a pet parent and your dog’s biggest advocate, to think critically when evaluating a diet.
It is important to remember that there is an abundance of misinformation that often goes against the science-based evidence.
Complete and balanced plant-based diets should be given equal consideration to meat-based diets, especially given the current understanding of pet nutrition, and the emphasis on nutrients not ingredients. Currently, meat-based diets are evaluated based on whether they meet AAFCO requirements for nutritional sufficiency and plant-based diets should be evaluated using the same criteria.
Wild Earth dog food is expertly formulated to not only meet but exceed AAFCO requirements for adult maintenance. Moreover, it is made with high quality ingredients and comes in several mouth-watering flavors. Take our quiz today to determine which of our formulas is right for your dog.
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