"Cats are obligate (strict) carnivores and are very different from dogs in their nutritional needs. What does it
mean to be an ʻobligate carnivoreʼ? It means that your cat was built by Mother Nature to get her nutritional
needs met by the consumption of a large amount of animal-based proteins (meat/organs) - not plant-based
proteins (grains/vegetables) " Pierson (2008)
The domestic cat is a prime example of an obligate carnivore. Cats must eat animal meat and organs to meet their nutritional needs. Plant-based proteins (grains and vegetables) simply aren't a good substitute. Cats lack the specific enzymes necessary to use plant proteins as efficiently as animal proteins.
The proteins derived from animal tissue contain a complete amino acid profile. Amino acids are the building blocks of protein. Plant-based proteins don't contain all the amino acids critical for the health of an obligate carnivore.
Humans, who are omnivores, have the physiological ability to turn plant proteins into the missing pieces needed for a complete amino acid profile. To a very limited extent dogs can do this, but a cat's body isn't equipped for it whatsoever. Cats also need much more protein in their diet than other animals. Kittens require twice as much protein than puppies. Adult cats need 2 to 3 times the amount adult dogs require. One of the reasons for this is because while other mammal species use most of the protein they consume for growth and body maintenance, cats use protein for those purposes and also as a source of energy. When other species of animals are fed a low-protein diet, their bodies make adjustments to conserve amino acids to manage the deficit, but a cat's body must continue to use protein even when there is not enough in the diet. This is why protein malnutrition happens quickly in sick or injured cats & anorexic cats. In addition to their increased need for protein, cats also have a higher requirement for certain specific amino acids found naturally in animal tissue. One of the amino acids missing in plants is taurine, which is found in animal muscle meat, in particular the heart and liver. Taurine deficiency causes serious health problems in cats, including cardiovascular disease and blindness. Dogs can make their own taurine.