Kery Shaw is one of many dog owners aligning their pets’ lifestyles with their own.
Ms. Shaw, a freelance photographer who lives in San Diego, was on medication for irritable bowel syndrome, migraines, allergies and recurring sinus infections when she learned about the health benefits of a plant-based diet. She decided to go vegan, abstaining from meat, fish, eggs, dairy and other foods made from animals.
On the new diet, her health improved so much that she wondered if Portland, her golden retriever who was suffering from bouts of diarrhea and itchy hot spots on the skin, could also benefit from a vegan diet.
She switched him from a meat-based dog food to v-dog, a vegan kibble that uses a pea-based protein and forgoes corn, soy and wheat, and saw his symptoms clear up. She supplements his diet with homemade smoothies and vegetables.
“He’s a cancer survivor, and he has way more energy than ever,” she said of Portland, who now has a clean bill of health.
Dog owners turn to plant-based foods for ethical, environmental and health reasons, noting that byproducts from mistreated or diseased livestock sometimes make it into foods and that animal agriculture is a leading source of greenhouse gases requiring copious amounts of water. Unlike cats, which are obligate carnivores (cats need nutrients found in meat to survive), dogs can draw the nutrients they need from animal or plant sources.
Makers of plant-based dog foods, which include brands like v-dog, Halo and Evolution, say their food meets the nutritional standards set by the Association of American Feed Control Officials, an organization of commercial feed producers and government officials that seeks to safeguard consumer and animal health. Vegan dog foods contain protein from plants like soybeans, potatoes or peas and are supplemented with the vitamins, minerals and amino acids, like vitamin B12 and calcium, that the feed organization recommends for dogs.
Veterinarians agree that dogs need a balanced diet, but are divided over whether plants and supplements make for an adequate meat substitute.
Dr. Lisa M. Freeman, a board-certified veterinary nutritionist and a professor at Tufts University, said that there were no long-term studies on the effects of veganism in dogs. A vegetarian herself, Dr. Freeman understands the ethical argument for avoiding meat but believes that a balanced diet for dogs should include meat. She recommends feeding a dog a high-quality fish-based diet as an alternative.
“We know a lot about dog nutrition, but there are unknowns as well,” she said. “We want them to be eating a diet that is nutritionally balanced. That means it has all the proteins, vitamins and minerals that they need in the correct ratios and with the best quality control. It isn’t easy to formulate a high-quality diet for dogs, and it’s particularly difficult with a vegan diet.”
A study published in 2015 in the Journal of the American Veterinary Medical Association that looked at vegetarian commercial pet foods found that of the 24 foods tested, most were not compliant with the minimum nutritional standards set by the feed producers’ group. Because some foods aren’t always formulated correctly, Dr. Freeman said, a meat-based diet from a reputable company is the best way to ensure that nutritional gaps are filled.
“If people are doing this because they are under the impression that it’s healthier, that’s just not true,” Dr. Freeman said.
While plant-based diets are known to have health benefits for humans such as reducing the risk of chronic illnesses like heart disease or Type 2 diabetes, pets will not necessarily get the same benefits.
“While dogs and cats get some of the same heart diseases that people do, they are very resistant to coronary artery disease, the main heart disease affecting humans,” Dr. Freeman said. “So the nutritional strategies that are beneficial for preventing heart disease in humans are not useful in dogs and cats.” Since obesity is the main risk factor for diabetes in cats and dogs, she said, maintaining a pet’s ideal body weight with a consistent diet is the key to successful treatment of that disease.
Dr. Michael Roth, a veterinarian in Richmond, Mass., and himself a vegan, said that some dogs have an allergy to common dog food ingredients like beef or dairy and that some may benefit from a vegetarian or vegan formula to help ease skin rashes and other allergy symptoms. He recommends that his clients try a vegetarian formula for 12 weeks to see if it relieves itching and improves the skin and coat. Many owners who see an improvement in their dogs, he said, are reluctant to move their dogs back to a meat-based diet.
“Is the vegan diet the best diet for all dogs out there? I don’t think anyone would say that, just like nobody would claim there was one best diet for all the people on the planet,” Dr. Roth said.
Dogs, like humans, have varying degrees of tolerance for certain foods, he said. He fed his most recent dog, Dawn, a golden retriever, a vegan diet. She lived to age 11 before developing a fatal cancer, about the same age that her brother, Sam, raised on a diet that included raw meats, also died of cancer.
Dr. Lorelei Wakefield, a veterinarian who regularly sees vegan dogs as part of a consultancy service she runs in the Philadelphia area, says that her clients do completely fine on the diet. “We don’t know yet what the healthiest diet is for them, but ethically, for someone who believes in vegan ideals, it makes sense,” she said.
Mary Straus, who runs a website called DogAware.com and writes for the WholeDog Journal, a holistic dog newsletter, disagrees. She says that some nutritional deficiencies take months and even years to show up in vegan dogs. Signs of malnutrition range from a dull coat and digestive issues to heart disease and early death.
“Our knowledge of nutrition is not great enough to ensure that this is the case, even if A.A.F.C.O. guidelines are met,” she said in an email, referring to the feed-makers’ group. “To be safe, a new set of guidelines would have to be developed for vegan diets, along with long-term testing to ensure that the diets actually meet the animals’ requirements. This has never been done.”
Ms. Straus, who feeds her Norwich terrier Ella a mostly homemade diet with meat, worries about the consequences of forcing dogs to eat a diet they were not designed for.
If you aren’t willing to give a dog the diet it really wants, she says, get a rabbit or a guinea pig: “There are lots of herbivores out there that make great pets.”