Diet and nutrition are perplexing subjects for many of us, and the confusion extends to our four-legged friends: BARF diet, homemade diet -- many dog or cat owners may have heard of these but are still not sure what they're all about. To help you, here's a quick look at four trendy alternative-food options. (Keep in mind that before making changes to your pet's nutritional intake, you should always check with your vet.)

1BARF

The premise behind BARF (Biologically Appropriate Raw Food or Bones and Raw Food) is to mimic the chow eaten by your dog's or cat's ancestors. These diets -- which gained visibility with the publication of Australian vet Ian Billinghurst's "Give Your Dog a Bone" in 1993 -- have no single formula but generally consist of unprocessed foods such as chicken carcasses (wings and necks intact with bones), ground vegetables, whole fish and eggs with shells. Advocates say they keep pets healthier and more energetic. Jane Morse, a holistic veterinarian at Ballston Animal Hospital in Arlington, says her BARF clients "look wonderful" but warns there are risks, including E. coli contamination and digestive intolerance. "Moderation and variation are important guidelines," she says. Others point out the absence of long-term studies on the diet's effects.

2Breed-specific

Proponents of this diet believe that the needs of, say, a papillon should be addressed differently than those of a giant schnauzer. While veterinary nutritionists don't recommend set diets for particular breeds, they can tailor them according to size and probability of genetic problems. For example, says Korinn Saker, director of nutritional services at the Virginia-Maryland Regional College of Veterinary Medicine, Bedlington terriers have "an identified copper storage disease; when clinical signs appear, it's recommended to feed a diet restricted in copper." These changes require a good veterinary nutritionist and cost money: At one site, www.petdiets.com, a $150 fee connects you with a certified nutritionist who can develop a custom diet for your pet. You can also contact the American College of Veterinary Nutrition (610-892-4812, www.acvn.org) for a nutritionist near you.

3Homemade

Nothing is more comforting than a home-cooked meal -- and some say it's the best option for pets, too. Most of these diets mix meats with grains such as rice or oatmeal, and add vitamins and minerals. Advocates say these offer higher-quality ingredients than commercial pet foods and can better serve pets with allergies or specific medical needs. They "can be digested and utilized more efficiently, creating a healthier animal," says Terri Grow, owner of the Alexandria animal health food store Pet Sage. The cons: Figuring out the exact ingredients to meet the complex needs of your pet can be confusing -- and time-consuming.

4Vegetarian

Having made the decision to cut meat out of their own lives, many vegetarians and vegans cringe at the thought of buying it for their pets. So some put their pets on homemade veggie diets or opt for the growing number of veggie choices available from pet brands such as Wysong, Natural Balance and Dr. Harvey's. Whether this route is healthy is up for debate. "Dogs and cats are not vegetarian," says Carvel Tiekert, executive director for the American Holistic Veterinary Medicine Association in Bel Air, Md. And most vets draw the line at feline vegetarianism: Dogs, like people, are omnivores, but cats are carnivores. Most vets recommend, instead, a diet of 80 percent meat and 20 percent greens.

Clare Leschin-Hoar

You think I notice what's in the food I eat? I just care that it's mine -- all mine!