Cats are known as obligate carnivores for several reasons:
- They have much higher protein and fat requirements than the majority of other mammals, and little need for carbohydrates.
- Many of the nutrients they require to live and thrive (such as taurine and arachidonic acid) are found only in meat.
- Unlike omnivores, cats can’t make their own vitamin B12 and vitamin A from plant matter, which means that they have to eat animals that can.
A cat’s natural diet consists of small prey such as birds, rodents, and in some cases small amphibians and reptiles. Other than the tiny amount of grass some cats consume and the partially digested plant matter they obtain from the digestive tracts of their prey, all of their nutrients come from meat. Cats that don’t consume these nutrients in sufficient quantities can suffer skin irritation, heart and liver problems, hearing loss, blindness, and even death.
Evidence That Cats Evolved to be Obligate Carnivores
There is plenty of evidence that cats evolved to live on an all-meat diet. According to Kirk, Debraekeleer, and Armstrong (2000):
- Cats don’t have receptors to taste medium chain fatty acids or sugars that are common in plant-based food sources.
- Cats have incisors and canine teeth for gripping prey and slicing tissue, and their teeth are less suitable than those of dogs for grinding up plant material.
- Cats have short gastrointestinal tracts, which don’t provide the extra time required to effectively digest plant-based materials.
- Cats don’t secrete some enzymes (and secrete very little of others) required to digest and derive energy from sugars commonly found in plants.
- Cats rely on protein more than carbohydrate for energy production (for omnivores such as humans and dogs, carbohydrates are a more important energy source).
- Aspects of the urea cycle in cats are designed to mitigate the risk of hyperammonemia, a potentially life-threatening condition associated with high protein diets in omnivores.
Can Cats be Vegetarian or Vegan?
Makers of good quality vegetarian and vegan cat foods add synthetic variants of the missing nutrients that cats would normally obtain from meat. However, the majority of veterinarians, veterinary nutritionists, and animal organizations say that cats require meat for optimum health, though there are a few dissenting voices in the debate. For quotations from experts on the subject, see Veterinarians on Vegan and Vegetarian Diets for Cats.
For arguments that have been made in support of plant-based diets for pets, see Vegan and Vegetarian Cats and Dogs. For information about the dangers of meat-free diets for cats, see Health Risks Associated with Vegan Diets for Cats.
References:
- Dunn, T.J., Jr., DVM. (n.d.). “Cats are Different.” ThePetCenter.com.
- Kirk, C.A.; Debraekeleer, J.; & Armstrong, P.J. (2000). “Normal cats.” In: Hand, M.S.; Thatcher, C.D.; Remillard, R.L., et al. Eds. Small Animal Clinical Nutrition. 4th Edn. Philadelphia, PA: WB Saunders Co., 291-351.
- Knight, A. (13 July 2008). “Vegetarian Feline Diets.” Vegepets.Info.
- Max’s House Animal Rescue Inc. (2003). “Feline Nutrition.” MaxsHouse.com.
- Pierson, L.A., DVM. (2010). “Feeding Your Cat: Know the Basics of Feline Nutrition.” CatInfo.org.
- Scientific American. (12 March 2009). “Veggie Cat Food? Why Not All Cats Need Meat.” ScientificAmerican.com.
Jennifer Copley - Jennifer Copley, BFA, BEd, has a diverse base of expertise that includes research, writing, education, pet care, and various other ...
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