WASHINGTON, Maine >> Susan Frank and her dogs spend their days shepherding hairy, black pigs with names like Bacon, Pork Chop and Yummy around a chunk of Maine woods. Her farm, which raises and fattens the rare American mulefoot hogs for slaughter, is essential to their survival, she believes.

Frank’s mulefoots are representative of a breed that was once the rarest of all U.S. livestock according to some agricultural censuses, and remains critically rare, according to the Livestock Conservancy. There are fewer than 500 registered, purebred, breeding mulefoots in the country (they are even more uncommon elsewhere), and Frank’s Dogpatch Farm accounts for a dozen of them, along with some 170 others, some of which are cross-breeds.

The way to save declining breeds of livestock, she argues, is to get people to eat them — thereby increasing demand that will lead to more breeding. She wants the mulefoot restored to its early 20th-century status as a premier pig.

The U.S. Department of Agriculture is listening. The agency is giving her $50,000 to help increase interest in products made with mulefoot meat, and Frank is spreading her gospel to chefs, restaurants and markets around New England and New York.

“I know it sounds weird, but you have to eat a rare breed to help it come back,” she said. “I see it as a way to spread the word about mulefoot.”

The mulefoot is named for its non-cloven hoof, and was the subject of a vibrant industry including some 200 herds a century ago. But its tendency for slow growth and small litters reduced its appeal for industrial pig farming, and the mulefoot was down to just one significant herd in Missouri a decade ago, when a slow drive to save the breed began.

Frank got into the business in 2012 after acquiring her first three purebreds. The pigs were popular with small farmers and homesteaders because of their hardiness and high yields of meat and lard, said Darlene Goehringer, a mulefoot farmer in Hurlock, Maryland.

“If nobody wants them for pork, who would keep them?” Goehringer said. “This isn’t like raising a parrot.”

The drive to save the mulefoot is motivated in part by the importance of preserving genetic stock, said Jeannette Beranger, a programs director with the Livestock Conservancy. Mulefoots, like other old breeds of livestock, are genetic storehouses that can’t be replicated if they become extinct, she said.

“Even though we’re not going to feed the world with mulefoot hogs, the reason you want to keep them around is because they might have qualities that might not be present in other commercial hogs,” Beranger said.

Frank’s farm has 20 acres of fenced-in birch, beech and hornbeam trees where the hogs roam free, noshing on feed pellets and the occasional apple or pumpkin. She wants to organize a food festival based around mulefoot products, with some wineries and breweries.

Until then, she’ll be raising her pigs and working to convince restaurants in food-crazy places like Portland, Boston and New York to use their meat.

“It’s not just to make a living for me,” she said. “It’ll help the breed come back.”