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Why Cats are NOT Vegetarian or Vegan

Updated: Dec 16, 2021

Just like anything that follows a fad, the pet food industry is certainly no different. Unfortunately, sometimes these trends are heavily influenced by humans based on our personal views and ideologies. Recently there has been a new emphasis on switching to a vegan or vegetarian lifestyle. These options may be viable for us, but it is certainly not so for our feline companions.

Anatomically speaking, unlike dogs and humans, cats are obligate carnivores (1, 2, 3). This means anatomically they are designed to consume and thrive on meat. Starting at the mouth, if you look at the teeth of a carnivore like a cat they are sharp, pointy and jagged meant for holding, tearing, grinding and crushing all indicative of a meat based diet. Herbivores on the other hand typically have teeth that are flat with a jaw that breaks down plant material by moving side to side (4, 5).

Systematically, unlike humans, felines have a very short digestive tract so food passes very fast and must be readily absorbable to be useful (6). Plant material takes much longer to be digested and broken down, so more times than not is passed through the system almost untouched (7).

Enzymatically cats do not have the enzymes responsible for breaking down carbohydrates which include grains, fruits and vegetables. They do however have the enzymes specifically for breaking down meats (8,9).

Meat the main component of a feline appropriate diet contains proteins essential for healthy muscles and organ integrity (10). It contains amino acids that help the body function in every imaginable way including metabolism (11), brain function (12) and healing (13, 14). Meat is said to have a complete amino acid profile meaning that all the amino acids needed to function can be found in meat in adequate levels, this is not true of plant based proteins (15). Humans can turn many plant proteins into the needed amino acids, however cats do not have this ability. Meat also contains important vitamins and minerals, some that only can be found in animal protein, not from plant sources. One of these include taurine, an ingredient only found in muscle and organ meats and completely essential to a cat’s diet. Without this a cat can suffer from blindness, heart problems and even death (16, 17).

Important saturated fatty acids are also found in meat in useable forms unlike many plant oils (18). Fatty acids are important for hormone production, energy, cell membrane formation and protection of vital organs (19). Saturated fatty acids in animal based proteins range from around 80-90% whereas plant based proteins only contain around 10-20% (20, 21).

Meat also contains higher amounts of water (22). Many cats are put on a diet primarily consisting of dry cereal bases. Just like their savannah inhabiting ancestors, domesticated felines tend to retain water despite the quantity available to them (23, 24). If they do not get adequate water from the water bowl, and their kibble contains only 10% moisture then where are they getting it? This lack of water eventually results in many common illnesses such as chronic kidney failure (25) and urinary tract infections (26).

Meat also has high bioavailability or an ingredient’s potential to be absorbed and used by the body (27). Meat sources are 90-95% bioavailable versus only around 70% in plant proteins such as soy products (28). This is why often you find that companions on dry cereal based diets have large, smelly stool because they are not completely absorbing what they are taking in (29).

In short despite human views and lifestyle choices, obligate carnivores like cats cannot thrive on diets of grains and vegetables. For humans becoming a vegan or vegetarian is usually for health or ethical reasons, but those beliefs should not be imposed on your feline companion. A vegan or vegetarian diet fed to a cat can result in at the very least detrimental health concerns if not death.


1 Legrand-Defretin, V (1994). "Differences between cats and dogs: a nutritional view". Proceedings of the Nutrition Society. 53 (01): 15–24. doi:10.1079/pns19940004 2 Stevens CE, Hume ID. Comparative Physiology of the Vertebrate Digestive System. New York: Cambridge University Press; 2004

3 de Sousa-Pereira P, Cova M, Abrantes J, Ferreira R, Trindade F, Barros A, et al. Cross-species comparison of mammalian saliva using an LC-MALDI based proteomic approach. Proteomics. 2015;15:1598–607. doi: 10.1002/pmic.201400083

4 d e Muizon, Christian; Lange-Badré, Brigitte (1997). "Carnivorous dental adaptations in tribosphenic mammals and phylogenetic reconstruction". Lethaia. 30(4): 353–366. doi:10.1111/j.1502-3931.1997.tb00481.x

5 Wang, Xiaoming; Tedford, Richard H.; Dogs: Their Fossil Relatives and Evolutionary History. New York: Columbia University Press, 2008. ISBN 0231135289, p

6 Ann Wortinger, BIS, LVT, VTS, "Cats: Obligate Carnivore," CVC in Kansas City Proceedings, Aug 1, 2010.

7 The Editors of Encyclopædia Britannica. “Digestion.” Encyclopædia Britannica, Encyclopædia Britannica, Inc., 8 Apr. 2016,

8 Morris JG. Idiosyncratic nutrient requirements of cats appear to be diet-induced evolutionary adaptations. Nutr Res Rev. 2002;15:153–168. [PubMed]

9 Morris JG, Trudell J, Pencovic T. Carbohydrate digestion by the domestic cat (Felis catus) Br J Nutr. 1977;37:365–373. [PubMed]

10 Latham MC (1997). "Chapter 8. Body composition, the functions of food, metabolism and energy". Human nutrition in the developing world. Food and Nutrition Series – No. 29. Rome: Food and Agriculture Organization of the United Nations.

11 Bremer, J. (1 October 1983). "Carnitine – metabolism and functions". Physiological Reviews. 63 (4): 1420–1480. doi:10.1152/physrev.1983.63.4.1420. ISSN 0031-9333. PMID 6361812

12 Fernstrom, J D. “Dietary Amino Acids and Brain Function.” Journal of the American Dietetic Association., U.S. National Library of Medicine, Jan. 1994,

13 Sinha, Shivam, and Satish Chandra Goel. “Effect of Amino Acids Lysine and Arginine on Fracture Healing in Rabbits: A Radiological and Histomorphological Analysis.” Indian Journal of Orthopaedics 43.4 (2009): 328–334. PMC. Web. 19 Mar. 2018.

14 Sahley, Billie J Ph.D, and Katherine M. C.R.N.A., Ph.D Birkner. “Heal with Amino Acids, c2014.” Natural Remedies, Pain & Stress Publications, 2011,

15 Food and Nutrition Board of Institute of Medicine (2005) Dietary Reference Intakes for Energy, Carbohydrate, Fiber, Fat, Fatty Acids, Cholesterol, Protein, and Amino Acids [1], page 691, from National Academies Press16 Duane E Ullrey, "Nutrient Requirements: Carnivores," Encyclopedia of Animal Science by Wilson G Pond and Alan W Bell, CRC Press, 2005, 670.

17 Huxtable RJ. Physiological actions of taurine. Physiol Rev. 1992;72:101–163. [PubMed]

18 Burri, Lena, et al. “Marine Omega-3 Phospholipids: Metabolism and Biological Activities.”International Journal of Molecular Sciences, Molecular Diversity Preservation International (MDPI), 2012,

19 Dutchen, Stephanie. “What Do Fats Do in the Body? - Inside Life Science Series.”National Institute of General Medical Sciences, U.S. Department of Health and Human Services, 15 Dec. 2010,

20 Reece, Jane; Campbell, Neil (2002). Biology. San Francisco: Benjamin Cummings. pp. 69–70. ISBN 0-8053-6624-5.21 "Feinberg School > Nutrition > Nutrition Fact Sheet: Lipids". Northwestern University. Archived from the original on 2011-07-20.

22 USDA, and FSIS. “Water in Meat and Poultry.” United States Department of Agriculture, May 2011,

23 Adolf, E. F. 1939. Measurement of water drinking in dogs. Am. J. Physiol.125:75-86

24 Chew, R. M. 1965. Water metabolism of mammals. Pp. 43-178 in Physiology Mammalogy, Vol. 2, W. V. Mayer and R. G.VanGelder, eds. New York: Academic Press.

25 Hodgkins, Elizabeth M. Your Cat: A Revolutionary Approach to Feline Health and Happiness. 1st ed., Thomas Dunne Books, 2007.

26 vet Caldwell, G. T. 1931. Studies in water metabolism of the cat. Physiol. Zool. 4:324-355.

27 “Bioavailability.” Merriam-Webster, Merriam-Webster,

28 Tomé, Daniel. “Digestibility Issues of Vegetable versus Animal Proteins: Protein and Amino Acid Requirements— Functional Aspects.” Sage Journals , The United Nations University, 2010,

29 Klein, Dr. David. “Self Healing Colitis & Crohn's 4th Edition (Paperback) by David Klein, Ph.D.” Vibrant Health Superstore, Living Nutrition Publications, 30 Nov. 2017,

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