Can you feed dogs and cats a vegetarian diet?
I recently had a heated argument with a friend who belongs to the extremist animal rights group People for the Ethical Treatment of Animals. She believes that not only should people not eat animal products, neither should animals. Accordingly, she only feeds her dog (a seven-year-old golden retriever named Hawthorne) a nonmeat diet, primarily a biscuit called something like Veggie Bites. I told her the poor creature is a carnivore and cannot subsist on such fare, but could offer no proof except that he walks kind of slow and funny and coughs a lot. She pointed out that so do I. I tried to think of someone with both the knowledge and courage and … hmm … Cecil, can you answer this one?
Sure, but you're talking to a reformed man, you know. After my last tangle with the no-meat bunch I decided that never again would an innocent animal die for my supper. Since then I've eaten only vegetarians.
Having checked around, I'd say that while feeding a veggie diet to a dog bespeaks a certain excess of zeal, Hawthorne won't necessarily suffer any harm from it. Though meat eaters by nature, dogs seem to adapt to a plant diet reasonably well, the main challenge being to make the stuff palatable enough that they'll eat it. (A recommendation from the Vegetarian Society of the UK: spice it up with — bleagh — Marmite.)
Some believe dogs have a greater need for meat-based nutrients during stressful times of their lives, such as puppyhood and pregnancy. During these times, and maybe all the time, you might want to use diet supplements or a specially formulated veggie pet food such as Nature's Recipe. Only a fanatic would keep a dog on a veggie diet if it obviously were failing to thrive.
Cats are another story. It's dangerous and probably futile to try to feed a cat a vegetarian diet. If denied meat at home cats likely will go hunting for mice and birds and so on. If unsuccessful, they may suffer serious health problems.
Cats require specialized micronutrients abundant in meat but not readily available from other sources. For example, cats that don't get enough of the amino acid taurine (only good source: meat) will suffer retinal degeneration and eventual blindness. Other nutrients they obtain primarily or solely from meat include arachidonic acid, vitamin A, vitamin B12, niacin, and thiamine. Cats also require more protein and less fiber than a typical vegetarian diet provides. (All this info comes from the Vegetarian Society of the UK, incidentally.)
You can buy supplements and veggie cat foods to make up for the deficiencies in a veggie diet to an extent. But many pet experts, including some vegetarians, say you'd be exposing your cat to a foolish risk.
If you're interested in vegetarianism primarily for health rather than ethical or ecological reasons there are less problematic ways to improve your pet's diet. You could get a better kind of pet food, for one thing. Donna Dunlap, co-owner of Chicago's Parkview Pet Shop, recommends the Precise, Solid Gold, and Abady brands, which among other things are preservative free.
For further discussion of vegetarian diets for pets see https://www.vegsoc.org/factsvegetariancats. Or you can read up on the subject in Dr. Pitcairn's Guide to Natural Health for Dogs and Cats by Richard Pitcairn and The Complete Herbal Book of the Dog by Juliette deBairacli Levy.