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Protein in dog and cat diets

A short guide to the role of Protein in dog and cat nutrition.

Protein

Protein is the foundation of a carnivore's diet. It builds muscles, enzymes, hormones and antibodies, takes part in wound healing and oxygen transport [1]. In a raw diet based on muscle meat, protein is usually in plentiful supply — the real problem is most often not "too few grams", but too low quality of protein.

Where it's found: Muscle meat (poultry, beef, lamb, game, rabbit), heart, fish and eggs provide a complete set of amino acids. Offal (liver, kidneys) has an excellent amino acid profile, but it is added for vitamins and minerals, not as the main source of protein.

Quality more important than quantity

Collagen from bones, cartilage, skins, ears, necks and feet counts in the calculator as "protein", but in terms of amino acids it is almost worthless — it has a negligible amount of tryptophan and sulphur amino acids [2]. A diet with 45 g of protein, where a large part is collagen, gives in practice less usable protein than a diet with 38 g coming from muscle and heart. Base it on muscle meat (70–80% of the meat part), not on collagen elements.

Species difference

The dog (a relative carnivore) regulates protein metabolism depending on the supply and, with a deficiency, is able to spare it to some extent. The NRC standard for an adult dog is about 25 g of protein / 1000 kcal [1].

The cat (an obligate carnivore) has constantly high activity of protein-degrading enzymes — it burns it regardless of how much it gets, so with a deficiency it reaches for its own muscles. That is why its requirement is roughly twice as high: the NRC standard for an adult cat is about 50 g / 1000 kcal [1].

Deficiency: Gradual loss of muscle mass (the animal loses weight despite eating), dull and brittle coat, slower wound healing, weaker immunity, in the young — growth inhibition. In BARF, a deficiency rarely results from a literally small amount of meat — more often from an excess of collagen or from too lean a diet, in which the body burns amino acids for energy instead of building tissues with them.

Excess: The myth that "too much protein destroys the kidneys" finds no confirmation in a healthy animal — the excess of amino acids is simply broken down, and urea excreted [1] [3]. Restricting protein makes sense only with existing kidney disease and under veterinary control. The only real risk of a high-protein diet is the so-called "rabbit starvation" — an excess of lean protein with a dramatic deficiency of fat (e.g. slimming on chicken breast alone without skin).

For the curious

Raw muscle protein is digested at over 90% and has a biological value above 90, whereas collagen — because of the lack of tryptophan — close to zero [2] [4]. In animals on a raw diet, blood urea (BUN) is sometimes physiologically higher than on kibble — this is a consequence of the higher protein supply, and not in itself a sign of disease. Always interpret it together with creatinine, SDMA and the clinical picture [3].

Sources

  1. National Research Council (2006). Nutrient Requirements of Dogs and Cats. National Academies Press. https://nap.nationalacademies.org/catalog/10668/nutrient-requirements-of-dogs-and-cats
  2. Li P, Wu G (2023). Amino acid nutrition and metabolism in domestic cats and dogs. Journal of Animal Science and Biotechnology 14:19. https://doi.org/10.1186/s40104-022-00827-8
  3. Hand MS, Thatcher CD, Remillard RL, Roudebush P, Novotny BJ (2010). Small Animal Clinical Nutrition, 5th Edition. https://www.markmorrisinstitute.org/sacn5.html
  4. Lyu Y, Wu C, Li L, Pu J (2025). Current Evidence on Raw Meat Diets in Pets. Animals 15(3):293. https://doi.org/10.3390/ani15030293