Since this subject has come up in the comments recently, and since I’m a food wonk (and a vegetarian, of sorts), I wanted to gather some info from my bookshelf on the subject of vegetarian and vegan diets for pets.
The first important point is to make distinctions between the two as some people use them interchangeably when they are actually two different diet plans. That said, I’m giving my own simplified definitions here (with a Wiki link!) based on my understanding of the most widely accepted terms.
A vegetarian pet diet would include plants and foods derived from plants (e.g. rice, tofu) as well as some foods from animals (e.g. eggs, yogurt). It would specifically exclude foods derived from slaughtered animals such as meat and bones.
A vegan pet diet would be plants only – all foods derived from animals would be excluded.
I’m using 3 pet diet books written by veterinarians for this post:
Home-Prepared Dog & Cat Diets by Donald R. Strombeck, DVM, PhD
Dr. Pitcairn’s Complete Guide to Natural Health for Dogs & Cats by Richard H. Pitcairn, DVM, PhD & Susan Hubble Pitcairn
The Nature of Animal Healing by Martin Goldstein, DVM
Dogs and cats are not anatomically and physiologically designed to be vegetarians. Cereals are also not nutritionally adequate because they do not satisfy some essential amino acid requirements. Thus, dogs and cats are not designed to consume vegetable or cereal products as the most significant parts of their diets.
I’m guessing here that Dr. Strombeck is possibly against vegan pet diets even though he used the word vegetarian. The reason I make this guess is because he does provide a number of vegetarian recipes for pets in the book and in fact states on page 90:
Completely balanced vegetarian diets can be fed to dogs without fear of causing any nutritional deficiency.
He goes on to note that vitamin B12 is found only in foods from animal sources and must be added weekly to a vegetarian dog diet. I did not find any references specifically to a vegan pet diet in the book.
Regarding cats, page 112:
[Cats] have some unique nutritional needs that a strictly vegetarian diet cannot satisfy. [...] If a cat is fed a vegetarian diet appropriate for human beings, it is likely that signs of a nutrient deficiency will eventually develop.
In summary, Dr. Pitcairn is a no on vegan dog diets and a NO on vegan cat diets.
My observation is that problems arise mostly when owners exclude all animal foods, including milk products and eggs, from their pets’ diets.
Regarding vegetarian dog diets, he is a yes – while cautioning that you must be careful with the nutrients – but no for vegetarian cat diets. He does encourage reducing the meat in pet diets as a generally good thing to do. Besides the global, ethical and environmental considerations about feeding pets diets that are high in meat, he adds on page 71:
Our primary health concern about feeding meat [...] is that meat is now the most polluted food source on the market.
Dr. Goldstein states on page 59 that he is a vegetarian himself but believes that dogs and cats need meat in their diets:
Specifically, they need more protein and calcium than a vegetarian diet can provide – which is also to say more protein and calcium than humans need.
He goes on to relate the story of a dog on a vegan diet who came to him in very ill health. He tested her blood and found that her immune system was draining protein from her muscles. She died very shortly after her visit.
This post is intended merely to share 3 individual opinions on meatless pet diets. It is not presented as the final word on the subject by any means. If you have an opinion on, or experience with, feeding a meatless (or even reduced meat) pet diet, please share in the comments.
I am hoping one day to keep some egg laying chickens as pets. I’d like to rely on them to supply a significant (but not exclusive) protein source for my dogs. I like the idea of knowing for certain that the eggs I’m feeding came from well cared for hens and that they are fresh.