Vegetarian and vegan diets

Vegetarian and vegan diets differ by how far they exclude animal inputs: a vegetarian diet excludes meat but may still include animal-derived products such as eggs or dairy, while a vegan diet excludes all animal products entirely. The critical message is that the species matters enormously. In dogs, which are omnivores with a carnivorous leaning, a carefully formulated and properly supplemented vegetarian or vegan diet can in theory meet nutritional needs, though the margin for error is narrow and ongoing monitoring is necessary (FEDIAF, 2024). In cats the situation is fundamentally different, because the cat is an obligate carnivore that depends on nutrients found naturally only in animal tissue. The clearest example is taurine, an amino acid the cat cannot make in sufficient quantity and whose deficiency can cause dilated cardiomyopathy and serious eye disease, a link firmly established in feline nutrition since the 1980s (NRC, 2006). Other critical needs compound the problem: arginine, whose lack can trigger acute and life-threatening ammonia toxicity, arachidonic acid, and preformed vitamin A, since cats convert plant beta-carotene very poorly. A vegan diet for a cat therefore demands rigorous synthetic supplementation of these nutrients, and veterinary consensus remains cautious to outright opposed because of the severe consequences if formulation falls short. For cats especially, this is never a choice to improvise, and it requires specialist veterinary advice. The underlying biology connects to the [therapeutic and veterinary diet](/glossary/therapeutic-and-veterinary-diet) and broader [life stage](/glossary/life-stage) needs. For more, see the [Petipedia glossary](/glossary).

Petipedia · Editorial team

General documentary information. For an individual animal, a veterinarian's advice takes precedence over any online content.