Mudi dogs, which are medium-sized and shaggy, piqued the interest of a museum director who gave the breed its name around 1930. The breed’s fans describe them as hardworking, versatile and vigorous, with the ability to herd sheep and hunt boar and rats.

They are also able to take part in canine sports like agility and dock diving. Kim Seiter, a dog agility trainer from Oak Ridge, New Jersey, who has four mudi dogs said that they’re “very perceptive, and they have a subtle quality.”

“They’re not for the inactive person,” Seiter said.

The Russian toy dog is descended from the small English terriers that gained popularity among Russian elites by the early 1700s. Dogs from the smaller breed usually weigh no more than 6.5 pounds and usually have a lively expression and demeanor, though breeders say they may not be as lively around strangers.

The mudi dogs — the proper plural is “mudik” — were featured on postage stamps in their homeland in 2004, as were some other Hungarian breeds.

AKC executive secretary Gina DiNardo said the Russian toy breed “thrives on being close to its humans, making a wonderful companion for an owner who can be with the dog a great deal.”

The AKC is the United States’ oldest purebred dog registry. It recognizes 199 breeds, including the two newcomers, and acts as a governing body for many dog shows.

Recognition requirements include having at least 300 dogs of the breed spread around at least 20 states and promulgating a breed standard that specifies ideal features, from temperament to toes. Many popular hybrid or “designer” breeds, such as Labradoodles and puggles, aren’t recognized, but it’s possible they could be someday if breeders decide to pursue it.

Some animal rights and welfare advocates deplore dog breeding and the market for purebreds, saying they spur puppy mills and strand adoptable pets in shelters.

The AKC says breeding can be done responsibly and preserves somewhat predictable characteristics that help people find and commit to the right dog for them.

The Associated Press contributed to this report.