Protein is the foundation of the diet and the main building material of a dog’s or cat’s body. Dogs and cats require more protein in their diet than non-carnivorous species. They use it to build muscles, enzymes, hormones, the immune system (antibodies), fur and claws, and for metabolic processes [1]. Protein supplies all essential amino acids, and in cats it is also an important source of glucose: the cat has poorly regulated, continuously active gluconeogenesis from amino acids, driven mainly by the brain’s constant demand for glucose [2] [4]. This is not a rigid enzymatic ‘block’—above its requirement threshold, a cat can partly adjust the rate at which it oxidizes protein [5]. Studies show that cats cannot regulate liver urea-cycle enzymes according to the protein concentration of the diet. Reduced protein intake therefore does not limit amino-acid breakdown, which is why the dietary demand for protein remains high [5]. Protein sources also differ between species: a dog is a facultative omnivore and a well-balanced complete diet can include plant protein [6], while cats practically require animal sources—not because ‘meat’ is a magical category, but because certain nutrients are found almost exclusively in animal tissues: taurine, preformed vitamin A, arachidonic acid and arginine [2]. Interestingly, increased protein intake has also been associated with a more diverse microbiota, for example bacteria of the genus Enterococcus [7].
What it contains: Pure muscle meat, offal, whole fish and eggs. Supplemental protein with lower bioavailability includes peas, lentils and soy. Protein sources differ in the amino acids they provide. Therefore, in healthy animals, while taking food allergies into account, it is worth using different types of meat in the diet.
Deficiency: This problem should not occur in a properly formulated BARF diet. It occurs with malnutrition: to survive, the body begins digesting its own muscles. This causes rapid weight loss, dulling and loss of fur, a drastic decline in immunity and impaired growth in young animals [1].
Excess: Contrary to outdated myths, a high-protein (meat-based) diet does not damage healthy kidneys in dogs and cats. A healthy carnivore metabolizes protein naturally and without difficulty; a higher blood urea level is then a physiological finding [1] [3]. Strict protein restriction is medically justified only when kidney problems or liver failure already exist.
Sources
- 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
- 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
- Hand MS, Thatcher CD, Remillard RL, Roudebush P, Novotny BJ (2010). Small Animal Clinical Nutrition, 5th Edition. https://www.markmorrisinstitute.org/sacn5.html
- Eisert R (2011). Hypercarnivory and the brain: protein requirements of cats reconsidered. Journal of Comparative Physiology B 181(1):1–17. https://link.springer.com/article/10.1007/s00360-010-0528-0
- Green AS, Ramsey JJ, Villaverde C, Asami DK, Wei A, Fascetti AJ (2008). Cats are able to adapt protein oxidation to protein intake provided their requirement for dietary protein is met. Journal of Nutrition 138(6):1053–1060. https://pubmed.ncbi.nlm.nih.gov/18492833/
- Domínguez-Oliva A, Mota-Rojas D, Semendric I, Whittaker AL (2023). The Impact of Vegan Diets on Indicators of Health in Dogs and Cats: A Systematic Review. Veterinary Sciences 10(1):52. https://www.mdpi.com/2306-7381/10/1/52
- Phimister, F. D., Anderson, R. C., Thomas, D. G., Farquhar, M. J., Maclean, P., Jauregui, R., Young, W., Butowski, C. F., & Bermingham, E. N. (2024). Using meta-analysis to understand the impacts of dietary protein and fat content on the composition of fecal microbiota of domestic dogs (Canis lupus familiaris): A pilot study. MicrobiologyOpen, 13(2), e1404. https://doi.org/10.1002/mbo3.1404