Cats are true carnivores. While you may choose a vegetarian lifestyle, don't assume it's healthier for your cat also. Cats aren't able to convert beta-carotene into vitamin A the way we can. They must get vitamin A from animal tissue (called preformed A). Cats are also unable to convert linoleic acid (an essential fatty acid) to arachidonic acid the way dogs can so they must get preformed arachidonic acid from its only source—animal tissue.
Pam Johnson-Bennett, Twisted Whiskers: Solving Your Cat's Behavior Problems
cats, feline-behavior, feline-nutrition