Research suggests that a vegan diet may be healthier, helping people lose weight and offering protection against heart disease, type 2 diabetes, and certain cancers. But what may surprise some is that a vegan diet may be the healthiest choice for dogs, too. According to a new study that surveyed the guardians of more than 2,500 dogs, canines that exclusively eat vegan chow may be healthier and less prone to disease than their meat-eating counterparts.

The growing appeal of vegan diets for dogs

Wolves, the ancestors of dogs, are carnivorous animals that primarily consume meat-based foods and do not actively seek out plant-based dietary supplements. Around 8,000 years ago though, the earliest domesticated dogs became omnivores, according to a 2021 study that analyzed Bronze Age dog poop and found microbes that help digest starches. The shift in diet allowed dogs to eat grains, fruit, vegetables, and other complex carbohydrates. In time, the genetic makeup of dogs further adapted to accustom to plant-based foods, including genes that produce amylase, an enzyme that is essential to efficiently digest starches to turn them into energy.

Dogs are thus perfectly capable of surviving on solely plant-based food, but that doesn’t necessarily mean that’s the most optimal diet for their health and longevity. In order to gather more evidence that might paint a more accurate picture of the benefits and drawbacks of a vegan diet for dogs, researchers led by Andrew Knight at the University of Winchester analyzed the self-reported data from the guardians of 2,536 dogs fed a conventional meat-based diet, raw meat, or vegan diet.

“There is increasing interest in alternatives to conventional meat-based diets (i.e., produced by commercial pet food companies), due to concerns about pet health, environmental sustainability, and the welfare of farmed animals used to produce meat-based diets. Accordingly, alternatives such as lab-grown meat, vegan, vegetarian, and diets based on yeast and seaweed, are being rapidly developed. Vegan pet foods are most developed, and the sector was estimated to be worth $9 billion globally in 2020, which is expected to rise to $16 billion by 2028. However, some are concerned that alternative diets are ‘unnatural’, and that this may somehow compromise the welfare of dogs. Accordingly, I set out to study health and behavioral outcomes when dogs are maintained on vegan vs. meat-based diets,” Professor Knight told ZME Science.

“As far as we could tell from a detailed analysis of the behavior of over 2,000 dogs, those fed vegan diets seemed just as happy with their meals as those fed meat. And our current study of over 2,500 dogs has demonstrated that the healthiest and least hazardous diets are nutritionally sound vegan diets.”

The data analyzed by the researchers included general characteristics such as the quality of the dogs’ coats and specific health disorders, as well as the number of veterinary visits and the use of medications.

The preliminary results showed that the dogs who were fed a raw meat diet tended to appear the healthiest. But on second look, these dogs were significantly younger and thus less prone to age-related health problems. Additionally, people who would feed their dogs exclusively raw meat were also less inclined to take their pets to the veterinarian. While this sounds like additional evidence that a raw meat diet protects dogs, prior research showed that the guardians of dogs on raw meat are less likely to seek veterinary advice even when they normally should have.

In light of these considerations, the researchers concluded that the diet most associated with healthy outcomes was vegan — and this wasn’t the first study to find this. In a 2014 study led by Pia-Gloria Semp, a veterinarian at the University of Vienna, researchers performed clinical examinations and blood tests on dogs who switched to a vegan diet. This study concluded that 39% of the participating guardians reported their dogs had healthier and shinier coats. Some animals that were previously prone to scaly or oily coats were now healthy.

Another study pitted a dozen Siberian Huskies against each other in a demanding sprint race. Half were fed either a commercial diet recommended for active dogs, while the other half ate a meat-free diet with the same nutrient specifications. The dogs were on these diets for 16 weeks, including 10 weeks of competitive racing. All dogs were found to be in excellent physical condition and none developed anemia or any detectable problems, despite the demanding environment. Furthermore, researchers claim that similar results apply to cats as well.

Both dogs and cats seem to enjoy plant-based foods at least as much as meat

“The studies published so far demonstrated that dogs and cats fed vegan meals appear just as happy as those fed meat-based diets, based on a very detailed analysis of their behavior. We also studied 29 pet food manufacturers. Plant-based pet foods were manufactured to standards slightly superior to those of meat-based pet foods. This new study found that nutritionally sound vegan diets are the healthiest and least hazardous dietary choices for dogs,” said Knight.

As for palatability, both dogs and cats seem perfectly happy with their new diets. A 2021 study conducted by Professor Knight and colleagues on 2,308 dogs and 1,135 cats found vegan pet foods were generally enjoyed at least just as much as meat-based foods.

But for Professor Knight, the fact that a vegan diet is healthier and more enjoyable for pets is only part of the story. Nearly 30% of the environmental impacts of animal agriculture in the United States are attributed to the manufacturing of pet food. Combined with the human population and pet growth, this important ecological “paw print” is only expected to increase. And although many may be unhappy to hear this, evidence points to the fact that both humans and their pets need to eat less meat and more plant-based foods in order to stave off environmental catastrophes.

“Considering vegan diets for dogs may seem alien to some. But we need to face the fact that meat-based pet food is contributing to environmental catastrophe, and also harms many millions of food animals used within its production. ‘Business as usual’ is not an option, if we want to fix these problems. We have to consider alternatives. And the evidence is clear: nutritionally sound vegan diets are the healthiest and least hazardous dietary choices for dogs, and dogs appear just as happy with these diets in general, as with meat-based diets,” the veterinarian said.

If you’re a guardian considering switching your pets’ diets to vegan, Professor Knight has set up a website where he has compiled all the most recent up-to-date information on the matter. You’ll find answers to your most frequent questions regarding the impact of vegan diets on pets, including their health and the nutritional value and palatability of these foods, as well as the impact on the environment.

The new findings appeared today in the journal PLoS ONE.