Dry versus canned. Dry cat food often costs less than canned, and it can be convenient for cat owners who want to leave food out for the cat while they're gone. Most veterinarians see no problem with dry cat food. Others say cats really need wet food, because they evolved to get moisture from their prey. Veterinarian Lisa Pierson at CatInfo.org says cats have such a low thirst drive that they'll never drink enough from the water dish, and dry-fed cats run the risk of painful, potentially life-threatening urinary problems.
Some vets recommend dry food to keep cats' teeth clean, but others, like Pierson, say that's a myth: "The idea that dry food promotes dental health makes about as much sense as the idea that crunchy cookies would promote dental health in a human," Pierson writes.
What about raw? Some cat owners and experts say it's best to feed cats what they would eat in the wild: raw meat, bone and organs. You can buy frozen raw cat food designed to closely mimic a cat's natural prey.
What's your budget? The very best cat foods -- tons of high-quality meat, no grains or fillers, nothing artificial -- are usually the priciest. But you don't have to spend a fortune to feed your cat well. For example, Trader Joe's Chicken, Turkey and Rice Dinner (*Est. 60 cents for a 5.5-oz. can) gets good reviews from cat owners and experts alike.
Watch for vague-sounding ingredients. For example, "chicken meal" is a decent cat food ingredient; experts say: High-quality versions include chicken meat and sometimes bone rendered to remove moisture (useful for making dry food). On the other hand, "meat and bone meal" can come from any mammal at all. "Animal digest" means soft animal tissue that has been "digested" into liquid form using enzymes. Although these are all legal pet food ingredients, top-rated foods don't use them.
Vegetarian food for cats? Some cat owners want to feed their cats vegetarian or vegan diets -- and some cat food companies manufacture them -- but this is controversial. Cats evolved as obligate carnivores that eat other animals, and almost nothing else. Vegan cat food advocates, including People for the Ethical Treatment of Animals (PETA), agree that cats do need certain nutrients that plants don't have, but they say vegan food can add supplements to cover that. Some cat owners say they've fed vegan food for years, and their cats are healthy.
But plenty of veterinarians aren't convinced. "For cats, it's really inappropriate. It goes against their physiology and isn't something I would recommend at all," Cailin Heinze, a board-certified veterinary nutritionist and assistant professor of nutrition at Tufts Cummings School of Veterinary Medicine, tells WebMD.com. Without proper supplements, vegan cats can't get enough of certain amino and fatty acids, and it can be hard for them to get enough protein, all of which can lead to growth problems, eye problems, reproductive failure and life-threatening heart disorders.
"For me, it boils down to this question: 'Why?'" veterinarian Jennifer Coates -- herself a vegetarian -- writes in her nutrition blog for PetMD.com. "Why have an obligate carnivore as a pet if you are not willing to feed him or her meat?"