Almost nothing changed when these dogs went vegan
Doges Editorial · 2026-06-16 · 5 min read
A new study from the University of Guelph fed 61 dogs a plant-based diet for three months, then checked their blood across hundreds of metabolic markers. The results were less alarming than most expected.
In a veterinary research lab at the University of Guelph in Ontario, sixty-one dogs were enrolled in a carefully controlled trial. Half were fed an experimental plant-based diet — no meat, no fish, no animal products of any kind, formulated to meet current industry nutritional guidelines. The other half continued eating a standard commercial meat-based kibble with comparable levels of protein and fat. Three months later, researchers drew blood, ran detailed metabolomics analysis across more than 200 individual compounds, and looked for differences. The study, published June 9 in Frontiers in Veterinary Science, found far fewer than most expected.
The question everyone keeps asking
Whether dogs can thrive on a vegan diet has followed the plant-based food movement into the pet food aisle, where it tends to generate more heat than evidence. Dog owners who avoid meat for environmental or ethical reasons ask it carefully; critics invoke wolves and evolutionary history. Previous studies have examined longevity markers and owner-reported health outcomes with mixed and sometimes methodologically uneven results.
This study, led by researchers at the Ontario Veterinary College, the University of Saskatchewan, and the University of Guelph's Departments of Animal Biosciences and Human Health and Nutritional Sciences, asked a more precise question: what actually happens to a dog's blood chemistry when you remove the meat from its bowl? Metabolomics — the study of small molecules produced during digestion and metabolism — offered a way to answer it at a level of detail that standard vet blood panels can't reach.
How the experiment worked
The trial enrolled 61 privately owned healthy adult dogs in Ontario. Thirty-one ate the extruded plant-based kibble; thirty ate a commercial meat diet. Both diets met industry nutrient recommendations for adult dogs, and both were adjusted to match each dog's existing intake to prevent weight changes from diet volume. The dogs lived at home throughout, owners recorded food consumption, and researchers collected blood samples at the start of the three-month period and again at the end.
The metabolomics panel tested 47 amino acid and protein markers, 16 carbohydrate metabolites, 29 compounds in the one-carbon and folate pathways, 61 fatty acids, and 78 lipid metabolites. It was, in the language of the study's methods section, a comprehensive attempt to find anything in the blood that changed. Most things didn't.
What the blood said
Zero of sixteen carbohydrate metabolites differed between the vegan and meat-eating dogs. Eleven of forty-seven amino acid and protein markers showed differences — most traceable to the simple fact that plant and animal proteins contain different amino acid profiles. The differences looked like dietary composition, not metabolic distress.
Dogs fed a plant-based diet for three months showed few metabolic alterations compared with dogs fed a meat-based diet. Those detected were mostly attributable to differences in dietary composition.
— Dodd et al., Frontiers in Veterinary Science, June 2026
The more notable findings appeared in fatty acids and lipids. Dogs on the vegan diet had lower total serum fatty acids and a lower omega-6 to omega-3 ratio — counterintuitive, because the plant-based kibble actually contained more fat than the meat diet. The authors suggest this likely reflects how the two diets' ingredients are absorbed and metabolized rather than anything alarming. Serum creatinine was also modestly lower in the vegan group; because the related compound creatine showed no corresponding change, the clinical meaning remains unclear.
What didn't change
On all the conventional measures that veterinarians actually act on — body weight, physical examination findings, complete blood counts, standard serum chemistry — the two groups were indistinguishable. No dog in either group showed signs of illness attributable to diet. The vegan dogs did not lose muscle. Their coats stayed normal. Their energy levels, as reported by owners and observed during clinic visits, were the same.
The plant-based pet food market is growing globally, driven partly by owners who have adopted vegan or vegetarian diets themselves and want their pet choices to be consistent. Market analysts estimated it at roughly $17 billion by 2030. But scientific evidence on whether dogs can safely eat meat-free food has been slower to accumulate than the market demand. This study is one of the more rigorously designed contributions to that evidence base so far — 61 dogs, a randomised controlled design, a validated nutritional protocol, and a level of biological detail that previous studies rarely reached.
Where the caveats live
Lead author Sarah Dodd and senior researcher Adronie Verbrugghe — both veterinary nutritionists at the Ontario Veterinary College — are careful about what the study doesn't prove. Three months is a controlled window, not a lifespan. All the dogs were healthy adults; puppies, seniors, and dogs managing existing health conditions may respond differently. The plant-based diet used was a commercially formulated extruded kibble meeting industry standards, not a homemade recipe. Metabolomics captures chemistry, not long-term outcomes.
Whether the differences in fatty acid profiles observed translate into any health consequence over years is a separate question that this study was not designed to answer. The researchers call for longer studies using plant-based diets of varying nutritional composition and trials specifically designed to follow dogs across different life stages. "Further research is warranted using plant-based diets of varying nutritional composition to determine longer-term physiological impacts," they write in the study's discussion.
Further research is warranted using plant-based diets of varying nutritional composition to determine longer-term physiological impacts and how these may affect and be affected by different life stages and health outcomes.
— Dodd et al., Frontiers in Veterinary Science, June 2026
What dogs can do that cats can't
One reason this question is specific to dogs is that dogs are genuine omnivores — unlike cats, who have obligate nutritional requirements for certain animal-derived compounds including taurine and arachidonic acid that cats cannot synthesize from plant precursors. Dogs have wider metabolic flexibility. They can convert plant-based amino acid precursors into several compounds that cats must get from meat. This biological difference is why vegan cat food remains medically contentious in a way that vegan dog food does not — and why the Guelph study is telling us something meaningful rather than just performing an impossible experiment.
The bowl on your kitchen floor
For dog owners, what this study offers is not a prescription but a data point: a well-formulated commercial plant-based diet, fed to a healthy adult dog, does not appear to produce the kind of metabolic alarm signals that critics have predicted. The blood tells a story of dietary difference, not dietary danger. Whether that data point matters to your individual dog depends on what your dog needs, what your vet advises, and what questions are actually driving the decision.
Sixty-one dogs didn't choose the plant-based kibble. But their blood didn't object to it — and that, for now, is a meaningful piece of information for anyone standing in the pet food aisle, trying to make a decision that feels right for the animal waiting by the door.