To most people, pet food is something that comes in a bag or can. The package might be illustrated with pictures of meat chunks, vegetables and grains, but what's inside is probably the most thoroughly processed food product on the market.

Still, quite a few dog and cat owners are deciding that packaged food isn't the only way to feed their pets. Over the last two decades, they've become a vocal movement advocating food for pets made with whole, fresh, minimally processed and usually raw ingredients.

If calling it a "movement" seems like hyperbole, consider that nearly a thousand pet owners in San Francisco and the North Bay alone belong to SF Raw, a raw feeders' buying group. Similar organizations have sprung up across the country.

Since the early '80s, dozens of books have been published on raw pet diets. There are raw feeding dog and cat breeders, animal rescue groups and shelters. There are also uncountable e-mail lists, websites and message boards where raw feeding is discussed. Veterinarians have reported a huge increase in the number of clients expressing interest in raw and homemade diets, particularly after the 2007 pet food recall.

Most of those people, when they did mention raw diets to their veterinarians, got a lecture about the dangers of homemade diets and raw foods in particular. A lot of vets think it's impossible to make a homemade meal for a dog or cat without a PhD in nutrition and a food laboratory in the garage. And a raw diet? Given the amount of bacteria in raw meat, they say, that's a recipe for sickness and death for your pets.

So why do so many pet owners insist on feeding raw diets to their pets? And why is the modern raw pet food movement not just alive, but growing?

If the terms "slow food" and "locavore" come to mind, you're on the right track. Modern raw feeders aren't crazy, back-to-nature hippies or indulgent pet parents trying to spoil their fur babies with grass-fed steak tartare. They're part of a much larger movement interested in doing right by farm animals, the planet and their local economies.

Commercial diets and the myth of "people food"

The roots of today's raw feeding movement go back to the early '80s, although feeding raw foods to dogs and cats is as old as domestication itself.

Commercial pet food in the United States was introduced in 1890, but it took several decades for the idea that "science and industry know best" to completely take hold. When I was growing up in the 1960s, my family and my friends' families fed their pets a combination of commercial foods, scraps from the butcher and the leftovers from our own meals.

By the end of the '70s, however, the multibillion dollar pet food industry had created a generation of pet owners and veterinarians who were absolutely convinced that dogs and cats couldn't survive without the scientifically formulated products known as "dog food" and "cat food." What we ate was "people food," and our pets couldn't eat it without developing any number of diseases caused by nutritional deficiency or excess.

Then, in 1983, a veterinarian named Dr. Richard Pitcairn wrote "Dr. Pitcairn's Complete Guide to Natural Health for Dogs and Cats," in which he challenged that pervasive belief, suggesting that a lifetime of processed food wasn't any healthier for our pets than it was for us.

I read Dr. Pitcairn's book in 1986 and, being a health food kind of person, thought I'd try his approach, and I convinced my mother to make the switch for her dog, too. Our animals thrived on their new diets, but for years we were the only people we knew who were feeding that way.

A few years later, the Internet put pet owners around the world in easy contact with each other, and I discovered lots of people were feeding raw to their pets. That nascent online community discovered and spread what turned out to be the next big thing in raw pet diets, a feeding plan known as the "BARF" diet.

Does your pet BARF?

Australian veterinarian Ian Billinghurst didn't name his raw diet after puppy puke. The name "BARF," which stands for "bones and raw foods," was coined on the Wellpet e-mail list, where Billinghurst's book, "Give Your Dog a Bone," was being avidly discussed.

Billinghurst wanted dog owners to reproduce the elements of a prey animal when they fed their pets. He recommended a diet of muscle meat, organs and bones along with pulverized raw vegetables, probiotics, cultured foods like yogurt and a few supplements.

While the specifics of the Billinghurst diet were a bit fanciful, it tapped into something that made a lot of sense to most pet owners. They began asking questions like, "What did wolves eat before domestication and selective breeding created the dog?" and "What was the diet of the wild cat like?"

Their answers, like Billinghurst's, often had more fantasy than science behind them, but the approach made enough of an impact that the pet food industry and veterinary profession took notice -- and it wasn't positive notice.

"You're going to kill your pets."

Opposition to raw diets was loud and powerful. Dogs and cats, critics insisted, had such specific and complicated nutritional needs that no one in a home kitchen could possibly get their diets right.

That argument convinced some people to stay away from homemade and raw diets, but it flunked the logic test for most raw feeders. If dogs and cats couldn't survive without commercial pet food, why did we have dogs and cats at all? After all, the 20th century was almost upon us when commercial foods were invented.

Besides, we could see with our own eyes that our raw-fed animals were not just doing fine, but doing better than they had on commercial foods. Certainly it was possible to screw up a home-prepared pet diet, but getting it right definitely wasn't beyond our ability.

Another objection was much harder to dismiss. Raw meat, eggs and dairy products, raw diet opponents said, were full of bacteria that could sicken our pets and even be passed to us. The only safe way to consume these foods was to cook them.

Some raw feeders were skeptical. Dogs and cats not only evolved while eating raw critters, guts and all, but dogs -- as well as predators like the cat -- ate rotten, decomposing prey. And dogs and cats both lick their own behinds. Surely a little bacteria won't hurt them.

Unfortunately, it's not that simple. From E. coli in hamburger to salmonella in produce, juice and peanuts, there's fecal bacteria getting into our dinner at nearly every stage of the agricultural food chain. Cooking has become the only way for most individual consumers to eradicate harmful bacteria in their food, and warnings against eating raw or "undercooked" meats, eggs and dairy products are everywhere.

While it's true that healthy dogs and cats are more resistant to food-borne pathogens than humans, it's not true that they can eat them with impunity. Furthermore, the industrialization of food production has resulted in different bacteria, in greater numbers, than anything dogs and cats evolved to handle.

Ironically, the most effective objection to raw feeding -- food safety -- has ended up being its strongest justification. That's because the very reason most people feed their pets raw and homemade food is that we've come to believe that processed foods aren't safe enough.

When our veterinarians lecture us about the dangers of raw meat, they may be trying to scare us back into the arms of the commercial pet food industry. Instead they often end up pushing us farther into the movement towards locally grown, in-season, sustainably produced fresh foods -- foods that we perceive are cleaner, more humane and better for our animals and the planet.

The big change

Once, my mom and I were the only people I knew who fed raw. Today, almost everyone we know has at least considered it.

Raw frozen diets are available in pet supply stores and even vet's offices now, most formulated in accordance with guidelines by the Association of American Feed Control Officials (AAFCO), a private organization that establishes standards for animal food and whose approval has become the imprimatur of pet food nutritional adequacy.

Veterinary opinion is still overwhelmingly negative, but even that's starting to change. While there were always a handful of holistic veterinarians who advocated raw diets for pets, today their more conventional colleagues are taking a second look at the practice. SF Raw maintains a list of raw-friendly veterinarians on its website, several of whom feed raw diets to their own pets.

Kasie Maxwell, who founded SF Raw in 2003 and has been feeding raw diets to her pets since 1989, agrees that raw feeding is part of a bigger movement -- one that's not really about pets at all. She called it a "Michael Pollan-esque thing."

"Most of our members buy from us because it's an affordable way to support sustainable agriculture," she said. "But it's more than that. We buy eggs from a woman's backyard chickens and milk from someone else's pet goats. Instead of supporting mega-corporations and companies in China, we're supporting the local economy. We're supporting our neighbors."