Feeding animals diets appropriate to their evolutionary biology is fundamental to their welfare, and misunderstanding of species nutritional needs causes preventable suffering.
Species-appropriate nutrition welfare failures are common because species-typical diets may be inconvenient, expensive, or unappealing to owners. Cats fed vegetarian diets develop serious health problems; rabbits fed primarily pellets develop dental and gut problems; guinea pigs without vitamin C develop scurvy. These are not exotic welfare concerns — they are everyday welfare failures in millions of households. The welfare solution is accessible and affordable: research species-specific nutritional requirements before acquiring any animal.