Vegan diet for dogs given the thumbs-up by scientists

The pet food market is ever-expanding, and as pet owners become increasingly conscious of their own diets and values, they are also seeking pet food products that align with those values. Vegan diets for pets have been growing in popularity, and a recent study conducted by researchers from the University of Illinois has found that at least two human-grade, lightly cooked vegan diets can provide adequate nutrition for dogs.

“Because people are feeding these diets to their pets, it’s important they be tested like all other foods to make sure they’re safe and ‘complete and balanced,’” says study co-author Professor Kelly Swanson.

The researchers tested two vegan formulas, one with a grain ingredient and one without, from Bramble, a company that makes human-grade dog food. They also tested a leading brand chicken-based kibble diet. The diets were fed to beagles for three weeks, and the researchers analyzed the dogs’ blood chemistry, fecal quality, and microbiome.

The vegan diets were veterinary nutritionist-formulated mixtures of whole foods, including lentils, garbanzo beans, sweet potatoes, butternut squash, apples, blueberries, peas, and carrots. The researchers confirmed that both vegan diets and the chicken-based diet met standards set by the Association of American Feed Control Officials (AAFCO) for “complete and balanced” nutrition.

“One thing to remember is that animals don’t have ingredient requirements, they have nutrient requirements. As long as they’re consuming the essential nutrients in the correct amounts and ratios, dogs can be vegan, vegetarian, or meat-eaters,” says Swanson. “Knowledge of ingredient composition and nutrient needs are critical, however. Anyone can slap together a vegan meal for their dog, but without careful formulation, you might have something that’s really imbalanced.”

In earlier studies, Swanson’s group showed that human-grade, fresh dog foods were highly digestible, resulting in dramatically less stool. However, the researchers found that the vegan diets in the current study did not generate any more or less stool than the chicken diet.

“It’s not a surprise, really. With these ingredients, there’s more fiber and oligosaccharides, which could be good for dogs that need to stay regular,” Swanson notes.

The research team was surprised to find that certain blood metabolites, such as blood triglycerides and cholesterol, were significantly lower in dogs fed the vegan diets. This could benefit obese pets and help maintain a healthy weight.

The team also noted positive changes in the fecal microbiome and the chemicals produced by those microbes in dogs fed the vegan diets. 

“There were some interesting and beneficial changes in the microbial community that I think reflect the blend of fibers that were present in the vegan diets. The fecal metabolites phenol and indole, both of which contribute to fecal odor, were dramatically decreased in those diets too. It’s still going to smell, but probably less,” Swanson says. “Overall, it looked like there were some beneficial shifts from a gut health perspective in dogs fed the vegan diets.”

Professor Swanson says he’d like to do head-to-head comparisons between human-grade diets with and without meat and dairy products, but for the first study showing how fresh vegan diets perform in dogs, the results are promising.

“No one had tested digestibility of these diets in dogs before this. We showed that these vegan diets resulted in desirable fecal characteristics, high nutrient digestibilities, and positive changes to certain blood and fecal metabolites,” he says. “For people who are interested in feeding their pets a vegan diet that aligns with their personal values, the diets we tested are a good choice.”

Swanson emphasizes that the diets studied were formulated by veterinary nutritionists. Homemade vegan dog foods may differ by not providing complete and balanced nutrition for dogs.

The study is published in the Journal of Animal Science.

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