Cats are classified as obligate carnivores, meaning that they must have meat in their diet to thrive. Classifying dogs is more challenging because they don't have the same specialized metabolic pathways as cats.

Technically, dogs belong to the family Carnivora, but they have some adaptations that allow them to feed on both meat and vegetable matter. That means they are frequently called omnivores, despite having several metabolic adaptations that can be classified as typically carnivorous.

According to a paper by veterinary nutritionist Wouter Hendriks of the veterinary school at Utrecht University in the Netherlands, these adaptations include a limited ability to synthesize arginine and a lack of salivary amylase.

Veterinary nutritionist Laura Gaylord says that because of these adaptations, dogs can be described as "carnivorous omnivores." For the 2023 North American Veterinary Conference in Orlando, Gaylord wrote that "natural feeding studies indicate that dogs do prefer to consume a diet containing 30% of energy from protein, with less than 10% of energy derived from carbohydrates."

In his paper, Hendriks concludes: "Both domestic cats and dogs are descendants of true carnivores, with cats having a relatively highly nonadaptive metabolism, while dogs have inherited a moderately adaptive metabolism due to the feast-and-famine lifestyle of their direct ancestor. The proposed classification of our domestic dogs as an adaptive carnivore and cats as an obligatory carnivore appear to be the most accurate. Knowledge regarding the ancestral diet of our domestic dogs and cats can provide important information and evidence to improve the nutrition of our modern-day domestic dogs and cats."

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Are dogs carnivores or omnivores?

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