Can dogs and cats go vegan?

Plus, this meat-based feed takes a toll on the environment. Some argue that because meat-based pet foods use up meat industry byproducts like blood, bones, kidneys and connective tissue that aren’t typically used for direct human consumption, they are a sustainable example of upcycling. But many of those ingredients are often processed into ingredients for human food, making pet food a competitive use that still increases meat demand. Meanwhile, only about 50 percent of the ingredients in pet food are byproducts of other industries, meaning the other half — including meat, grains and more — are produced entirely for pets. Even when accounting for the fact that pet food consumes waste and byproducts, researchers have found that dog and cat food in the U.S. is responsible for 64 million tons of CO2 emissions annually — equivalent to the emissions of about 14 million cars. All in all, researchers estimate that pet food is responsible for about 25 percent of the U.S. meat industry’s environmental footprint. That contribution is only expected to increase as more pet owners adopt “luxury” pet foods that incorporate meat, fish and poultry that could also be eaten by humans.

The problem is growing as pet guardianship increases rapidly around the world. In fact, there are more than 528 million dogs and 476 million cats worldwide. Plant-based pet food provides an opportunity to dramatically reduce what the industry calls its “environmental pawprint” and benefit pets, humans and other animals alike.

Plant-powered pets

To start, a top concern with any diet is its impact on the pet’s health. But that varies for dogs and cats, since what they eat differs. Omnivorous dogs can eat both plants and animals, while cats are obligate carnivores, meaning they need a high-protein, low-carbohydrate diet. Yet, in dogs, studies of plant-based diets yielded surprisingly positive results. For example, a study of vegan dog food found it to be nutritionally complete, while dogs fed this diet had lower levels of circulating fats in their blood versus those on a chicken-based diet. The researchers also found vegan diets had higher levels of health-promoting fiber.

“We did see a lot of interesting changes from a gut microbe perspective and the metabolites … ,” said Kelly Swanson, the director of the Nutritional Science Division at the University of Illinois, Urbana-Champaign. “Definitely a lot more of the bacteria that are really fermenting fibers and carbohydrates are there versus if you would have a high-protein, high-fat diet. So, we had a beneficial shift in the microbiota.”

Swanson explained that products from fiber fermentation limit pathogen growth and support gut health and satiety. They also aid the gut barrier function, or the intestines’ ability to absorb nutrients, water and minerals while keeping pathogens out of the bloodstream. Further, a review of numerous scientific studies didn’t consistently find adverse health effects, and even identified potential benefits associated with vegan diets for dogs and cats. (It’s worth noting, however, that most of these studies were on the scale of weeks to months, and many of the cats were given supplements, which may have helped maintain their good health.)

“First, purchasing vegan pet food is a consumer lever that potentially reduces demand for animal-derived ingredients and opens markets for animal-free alternatives … ,” said Halteman. “Second, vegan options for pets invite people to extend their circle of moral concern across species boundaries in a more consistent way. When we start asking, ‘Can I care for this animal without harming those animals?’, we’re expanding our moral imagination in a way that I think has important ripple effects well beyond the food bowl into our everyday attitudes and actions toward other human beings, wildlife on our properties and even the world as a whole.”

On top of these ethical advantages, Halteman has noticed a personal benefit from feeding his dogs a vegan diet.

“In the days when we just bought any old kibble, I wasn’t nearly as informed about what dogs need to thrive … ,” said Halteman. “It’s also helped me to understand feeding as an ethical practice that has impacts beyond my consumer choice. As a philosopher, I love practices that invite me to be intentionally engaged in life rather than asleep at the wheel.”

Despite these advantages, the current cultural trend (among humans) of consuming large amounts of protein, or proteinmaxxing, doesn’t always align with plant-based diets.

“More [protein] is often assumed to be better, and protein is sometimes taken as synonymous with animal products,” said Halteman. “This can create skepticism among the public about plant-based diets (at least among those more influenced by trends and fads than the scientific consensus), even though protein adequacy is entirely achievable without animal sources when diets are properly designed. For our companion animals, as for human beings, the question isn’t ‘Is there protein?’ but ‘Is there enough of the right amino acids, in digestible forms, for this particular body?’ Unfortunately, the fad of ‘maxxing’ can eclipse more informed conversations.”

From prey to plants

Despite the obstacles, pet guardians are increasingly open to new diets. A study of both cat and dog guardians found that at least 43 percent were open to more sustainable diets, including vegan food.

For people interested in a plant-based diet, there’s a variety of pet food brands already available, such as Virtuous Vittles, Wild Earth Pet Food and Just Be Kind. Plus, following a few simple tips can help your companion adapt, including transitioning their diet gradually over a few weeks, gently warming wet food and mixing tasty additions, like nutritional yeast, vegetable oil or nori flakes, into the food. Watching your pet during the transition is important, too.

“Make sure they’re maintaining body weight and adapting over time,” said Swanson. “So, they’re maintaining a healthy body weight, not overeating, not undereating, which is similar to every pet diet that I would recommend.”

Even just incorporating more plant-based foods into a pet’s diet can be beneficial.

“At the end of the day, even if you can only get halfway there, don’t criticize yourself too much,” said Knight. “This isn’t about vegan purity. This is about doing as much good as you can. If you just get half of the potential health benefits for your pet and half of the environmental benefits, that’s not nothing. That can still be really significant.”