Dogs and Cats Can Be Healthy, Happy Vegans, Research Shows

Can cats be healthy, happy vegans? Many people categorically say "No!"—end of story. Others say things like, "Maybe, but I'm not sure, and I remain skeptical," whereas still others are happy to learn what research tells us is possible and say, "I'm happy to try."

To help provide more information on this "hot" topic, I went right to the expert on these matters, veterinary professor of Animal Welfare Andrew Knight, who has been studying feline and canine diets for many years.

I'm pleased Andrew could answer a few questions that focus on two recent open-access data-driven seminal studies, the first that shows the health and behavioral benefits of vegan diets for cats and dogs—"Vegan versus meat-based cat food: Guardian-reported health outcomes in 1,369 cats, after controlling for feline demographic factors"—and the second that shows the sustainability and environmental benefits of plant-based meals for dogs, cats, and humans—“The relative benefits for environmental sustainability of vegan diets for dogs, cats, and people." All in all, data show that moving toward plant-based diets is not a fringe "radical" move but rather one that has a sound foundation in solid science. Outdated myths need to be put to rest.

Marc Bekoff: Why did you do this most important research, and how is it related to your background, interests, and expertise?

Andrew Knight: We’ve long known the food system was important for environmental sustainability, and that transition toward plant-based diets was essential, if we’re to slow climate change and environmental degradation. However, we’ve always assumed this applied only to human diets. We’ve rarely considered such diets for our dogs and cats. As a veterinarian, I wanted to explore the potential benefits for environmental sustainability, of nutritionally sound vegan diets for dogs and cats. My related research has also explored health and behavioural outcomes.

MB: What are some of your major findings?

AK: I started by analysing pet food ingredients in detail, and also examined ingredients within human diets. I determined the environmental impacts of those ingredients and examined how these would change if the same dietary energy was provided solely by plant-based ingredients—i.e., within vegan diets.

• The results demonstrated that the world’s dogs and cats consume at least 9 percent of all land animals killed for food, or around 7 billion animals annually, as well as billions of fish and aquatic animals.
• If all the world’s dogs went vegan, it would save more greenhouse gases (GHGs) than all those emitted by the United Kingdom, land larger than Mexico, freshwater exceeding all renewable freshwater in Denmark, and would feed around 450 million additional people—more than the entire European Union.
• If all the world’s cats went vegan, it would save more GHGs than all those emitted by New Zealand, land larger than Germany, freshwater exceeding all renewable freshwater in Jordan, and would feed around 70 million additional people—more than the entire United Kingdom.
• And if all the world’s people went vegan, it would save more GHGs than all those emitted by the entire European Union, land larger than Russia—the world’s largest country, combined with India, freshwater exceeding all renewable freshwater in Cuba, and would feed around 5.3 billion additional people—two-thirds of the Earth’s current population. All of these estimates are conservative.

Source: Courtesy of Andrew Knight

MB: Why should people pay close attention to these significant novel findings and how can they put them into action?

AK: This study shows that the environmental impacts of meat-based pet food are very large indeed. Conversely, great benefits for environmental sustainability are available, if we transition our dogs and cats onto nutritionally sound vegan diets. Related studies in this field—including recent, large-scale studies, have shown that health and behavioural outcomes are as good or better when nutritionally sound vegan diets are used. To safeguard health, it is important that pet guardians feed only commercial diets labeled as nutritionally complete, produced by reputable companies with good standards.

MB: What sorts of resistance do you think will come your way?

AK: Until recently, vegan diets were not seriously considered for dogs and cats—who are biologically omnivores and carnivores, respectively. In the last two years, however, many new vegan pet foods have been developed by companies using plant-based ingredients supplemented with vitamins, amino acids, and minerals, to ensure all necessary nutrients are included.

New studies have shown good health outcomes for dogs and cats using vegan diets. By September 2023, there were nine such studies in dogs and three in cats. Recent very large-scale studies have shown health outcomes as good or better for both cats and dogs fed vegan cats. And a very large-scale study of feeding behaviour demonstrated that dogs and cats enjoy vegan pet food as much as meat-based pet food, on average.

MB: Are you hopeful that people will see the importance of this scientific research and not write it off as some "radical" agenda?

AK: Yes, indeed. In 2023, the Intergovernmental Panel on Climate Change noted that “Climate change is a threat to human well-being and planetary health (very high confidence). There is a rapidly closing window of opportunity to secure a liveable and sustainable future for all (very high confidence).” In response, United Nations Secretary-General António Guterres stated, “Our world needs climate action on all fronts—everything, everywhere, all at once.” This certainly includes the food system. To date, calls for a transition to plant-based diets have largely focused on people. However, dogs and cats are also major consumers of livestock animals.

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If we are to secure a liveable future for all, then "business as usual" is not an option. Significant societal changes are required, especially in the sectors most responsible for climate change. This certainly includes the livestock sector. With nutritionally sound vegan diets now becoming available for dogs and cats, as well as for people, there is no good reason not to change, and there are compelling environmental reasons to do so.