Are vegetarian dog foods ok for dogs? What about vegan dog foods?
I have been a vegetarian for the last 25+ years of my life and am very sympathetic to ethical issues surrounding animal use as food. That said, a vegetarian diet can be appropriate for adult dogs. There are many brands out there which offer vegetarian options. However, these can sometimes be deficient in taurine and l-carnitine, both of which are normally of animal origin unless synthetically produced.
Also, vegetarian diets can be problematic for growing animals and there are no diets which have an appropriate protein content for a puppy (that I am aware of) currently on the market. Both taurine and l-carnitine can be purchased in bulk at reasonable prices; if there is a concern over improper supplementation, check the ingredients or call the manufacturer to discuss. If the diet needs to be supplemented, consult your veterinarian.
Another possible issue with a vegetable and grain based diet is an increase in urinary pH and, depending on the vegetable sources, an elevated oxalate content. Both of these can select for urinary crystals and bladder stones.
Vegan diets can be more problematic since ingredient choices are more limited. Also there are no commercially available vegan dog foods on the market. Therefore, a vegan diet would need to be home cooked. You would also need to consult a board certified veterinary nutritionist to have a balanced diet recipe formulated for you to make at home. And any recipe is likely to still use supplements that come from animal sources.
That said, dogs are omnivores and as a species are designed to eat animal-based food sources as well as plant-based ones. This is not to say they cannot be vegetarians/vegans, but it is not a part of their natural history. There may be other disadvantages or health implications to committing them to this kind of diet, though as of yet it has not been an issue.
The bottom line is that you need to be cautious when going this route and make sure that whatever diet you are feeding is either from a reputable manufacturer or the recipe you are following has been properly formulated to meet the complete nutritional needs of your dog.
Finally, it is worth mentioning that cats are obligate carnivores and cannot eat a vegetarian diet no matter how conscientious the formulation is. Feeding a cat this kind of diet is not only unhealthy but cruel.
– Dr. Phil Villard