One of the most common arguments against feeding dogs and cats vegan or plant-based diets is that they can’t digest plant ingredients because they evolved from carnivores. This perception isn’t helped by the number of pet foods marketed as grain-free, which adds to confusion and leaves people wondering whether grains are okay.
So one of research pieces I’ve been working on is a review of what the studies in this field demonstrate. This study, now published in the peer-reviewed journal Animals, reviews 31 studies that examined how well vegan, vegetarian and plant-based diets and their main ingredients are digested by dogs and cats. Digestibility is important because it tells us how effectively animals can absorb and use the nutrients in their food.
The review found that modern, nutritionally sound vegan diets are generally well digested by both dogs and cats, with digestibility broadly comparable to conventional meat-based diets. I say ‘modern’ because as with any diet, nutritional formulation matters. But ingredients such as wheat gluten, soy, peas, lentils, chickpeas, rice protein, potato protein and quinoa have all been shown to be highly digestible.
Knight A (2026). The digestibility of vegan and vegetarian diets for dogs and cats. Animals 6(10), 1454. https://doi.org/10.3390/ani16101454