Can pets eat vegan? Definitely maybe, says Dr. Ernie Ward

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As more and more Americans shift to a plant-based diet and feed their families less meat, some of them are bringing up the big question in the veterinary exam room: “I'm vegan. Can my pet be vegan?”

What do industry sources say about a plant-based diet?

Dr. Ernie Ward is optimistic that nutrition science and technology can make it possible for animals-even those known as “obligate carnivores”-to survive and thrive on plant-based diets. But where do other DVMs stand? Opinions are mixed.

Dogs can go veggie …

• Be careful. AAHA's 2010 Nutritional Assessment Guidelines for Dogs and Cats mention vegetarian diets as something to watch for: “Evaluate risks of vegetarian diets, particularly with cats but also with dogs.”

• It can work. The American College of Veterinary Nutrition (ACVN) website points pet owners to a 2006 resource from the National Academy of Sciences explaining that dogs are omnivores and are “remarkably adaptable to a wide range of ingredients” (provided they get their protein and nutrient needs covered). But the ACVN also cautions against home-prepared plant-based diets that haven't been vetted by a veterinary nutritionist: “[Some] owners wish to feed their pets according to their own philosophical views, and choose home prepared diets that are vegetarian, organic or raw. … There are many recipes for home-prepared pet diets available on the Internet and in books; however, the vast majority of these are inadequate and unbalanced. … Consider getting a customized recipe and consultation with a board-certified veterinary nutritionist.”

• It needs guidance. A nutritionist at Cummings Veterinary Medical Center at Tufts University, Cailin R. Heinze, VMD, MS, DACVN, said on the Petfoodology website in 2016, “Most dogs can do quite well on a carefully designed vegan diet that meets all of their nutritional needs” (emphasis Dr. Heinze's).

… but cats cannot

• Cats evolved to eat meat. The ACVN points cat owners to a National Academy of Sciences piece on cats that states, “The particular chemistry and structure of the cat's gastrointestinal system is well-suited to digesting and absorbing nutrients from animal-based proteins and fats. Unsupplemented vegetarian diets can result in harmful deficiencies of certain essential amino acids, fatty acids and vitamins.”

• Plant-based cat diets are out. Another nutritionist on Tufts' Petfoodology website chimed in last year that a solely plant-based diet for cats is a no-go. “Cats have special dietary needs that omnivores do not have and for this reason they should not be fed as vegetarians and should always have some animal protein meat in their diets,” writes Deborah Linder, DVM, MS, DACVN, adding a caveat that cats can't eat only meat either: “Cats can digest and utilize nutrients from plants and a very high or all-meat diet is dangerous for cats!”

Especially in the case of cats, typically considered obligate carnivores, the answer is a hard “no”-right? Ernie Ward, DVM, who's spent years thinking about animal nutrition and founded the Association for Pet Obesity Prevention, says, “Not so fast.”

First, Dr. Ward, coauthor of the upcoming book The Clean Pet Food Revolution: How Better Pet Food Will Change the World and chief veterinary officer at pet food company Wild Earth, says we've got to get the terminology right. And “vegan” is a loaded term that belongs to people and not animals.

“I don't think the term ‘veganism' applies to dogs and cats,” Dr. Ward says. The term “veganism” can stand for both a diet free of animal products as well as a philosophy about how animals can and should be regarded in the world.

“That's an ideology with an ethics structure and political implications,” he says. “We need to get past that and ask whether cats and dogs can survive without eating other animals.”

Here's where Dr. Ward departs from many veterinarians and pet owners who believe either 1) that we don't know enough about nutrition to try to build a plant-based diet for animals used to eating animal products or 2) that animals should be eating more whole foods (thus, getting their nutrients from natural food sources, often from other animals). He is optimistic that nutrition science and technology can make it possible for animals-even those known as “obligate carnivores”-to survive and thrive on plant-based diets.

No meat, no pets on Mars

Dr. Ernie Ward's thinking on pet nutrition is individual (everybody's body is different), but also global. To boot, it's interplanetary.

Nutritionists need to explore alternative nutrient and protein sources both to find plant-based diet alternatives today and to alleviate tomorrow's reliance on expensively produced meat. And as the human population increases, he also thinks it's crucial that everyone ask a question: How do we get pets onto Mars? In other words, how can we afford to feed pets that aren't “necessary” to our survival but enrich our lives immensely?

Dr. Ward thinks about a future where humankind is impoverished by its lack of relationship with the animals closest to them: “Will future generations look back nostalgically at these furry, dirty things, or will we continue to coexist with animals?” he asks.

In the upcoming book The Clean Pet Food Revolution: How Better Pet Food Will Change the World, Dr. Ward and his coauthors are looking at growing fungus to produce the necessary amino acids and other nutrients people-and pets-need to survive here and in space.

“There's no plan for pet food in space travel,” he says. “So, if we can figure out a way to feed everybody, now a small dog or cat or gerbil or hamster can make sense.”

Dr. Ward used to tell audiences that there are no pets on Star Trek (we're not counting those troublesome Tribbles), but his unspoken thought has always been, “Shouldn't there be?”

“The way physiologies work, we need certain nutrients, not ingredients,” he says. “But we have ingredient bias based on our own experiences, our cultures, what's locally acceptable.”

For example, some cultures eat a lot of dairy; others call it gross. Some cultures eat insects; others cringe at the thought.

“What happens as soon as you put a whole food or particular ingredients in your mouth?” Dr. Ward asks. “It starts being reduced to its constituent nutrients. How we access those nutrients is what makes all the difference.”

And that's where pets' individual differences-their genetics, their gut flora, their microbiome, the health of their pancreas, liver and kidneys-come into play. No matter how great a product is, he says, not every diet will ever be appropriate for every animal.

Science is advancing rapidly in this arena of personalized nutrition, according to Dr. Ward. Someday we will know far more about what both humans and pets need for their bodies need to be healthy and strong.

So, if a pet can get the nutrients it needs from a protein source other than cows, chickens, sheep or fish-and you can demonstrate it through science-do the actual ingredients matter?