Can cats and dogs be vegetarian?

Dogs can go vegan with the help of professionals, while cats are obligate carnivores.

After giving up meat for ethical, health or environmental reasons, some people want their pets to also partake in a plant-only diet. However, not all pets can eat this diet. Pet owners should not arbitrarily switch them to a completely vegetarian diet, according to Lindsey Bullen, veterinarian and animal nutritionist in North Carolina, USA.

A woman feeds her dog carrots in the garden.

Changing your pet's diet without professional help is often harmful to their health. The animal protein that dogs and cats typically eat contains many amino acids in a form that is easily absorbed by their bodies - more than what is normally found in plant proteins. Pets that don't get enough protein can lose weight, lose muscle, become weak, digest poorly, and even develop fluid retention in the chest or abdomen, according to Tufts University's Cummings Veterinary Medical Center.

Cats need taurine, an amino acid found in animal protein. Without the right amount of taurine in a plant-based diet, cats can have impaired neurological function, reproductive problems and heart disease, says Bullen.

The wrong mineral balance will also have consequences. For example, the wrong calcium-phosphorus ratio can increase the risk of bone fractures in dogs and cats, and delay the growth of puppies or kittens.

"Vegetarian diets can be safely applied to both cats and dogs. Meanwhile, vegan diets can be safely applied to dogs but very difficult for cats," Bullen said. Cats are obligate carnivores, so many of their nutritional needs are tied to the ingredients of the meat. As a result, cats need a lot of supplements to create a complete and balanced vegan diet.

Bullen encourages people to be actively involved in regulating their pets' diets, but cautions against anthropomorphizing them. "Dogs and cats are very different from humans. Your goals for yourself are fine, but we need to keep pets happy and healthy," commented Bullen.