Whether pug, pointer or Pekingese, pooches drift in and out of popularity just like hairstyles and skirt lengths, according to new research from a Western Carolina University professor.

"Dogs have become fashion statements," Herzog said. "In that regard, they're no different from popular movies or hot foods or things like that."

Herzog's research was published last month in the Royal Society's Biology Letters, a British journal. His co-authors are Alexander Bentley of University College London and Matthew Hahn of the University of California-Davis.

The authors concluded that the changes in breed popularity over time follow a pattern they call cultural drift, which they said is similar to random genetic drift in biological evolution.

Long ago, people picked dogs for their hunting or herding skills. These days, though, man doesn't make rational decisions in choosing his best friend.

Instead, dog owners appear to be copycats. People probably don't even know it, Herzog said, but their choice in dogs is based on those of their friends and neighbors.

"What happens," Herzog said, "is a breed will catch fire and it will become very popular."

Consider the poodle.

In 1952, there were only 6,000 poodles registered in the United States. By 1967, poodles were the thing, with 250,000 registrations. There's no explaining it, except that poodles were in vogue, Herzog said.

Last year, the American Kennel Club recorded about 32,000 poodles.

Sometimes, a dog breed's popularity is influenced by external factors. A decline in Rottweilers is likely linked to negative publicity about Rottweiler attacks in the late 1980s and 1990s, Herzog said.

And the club's data showed dramatic fluctuation in the prevalence of Dalmatians after the reissue of the animated movie version of "101 Dalmatians" in 1985. Dalmatian registrations soared sixfold over eight years, followed by a steep decline six years later.The same thing happened with Old English Sheep dogs when the film "The Shaggy Dog" was released in 1959.

Other mass-media events have less influence. There was no significant rush for Chihuahuas after a series of famous Taco Bell commercials in the 1990s.

Herzog has studied the interaction between humans and animals for 20 years. He has researched cockfighting, animal activists and attitudes about animals used in medical research.

When he persuaded the kennel club to give him more than five decades of data, he was giddy with the possibilities.

"Nobody had ever looked at it," he said. "For a data geek like me, it was just the mother lode."

Next, Herzog will analyze geographic patterns in dog ownership: The club has given Herzog access to dog registrations by ZIP code. He expects to find some interesting regional differences.

Though dog breed popularity appears to spread like a contagious disease, that doesn't mean some people don't draw reasoned conclusions about their canines.

Richard Davis of Saxapahaw did some checking into different breeds last year before deciding on Josey, a Doberman Pinscher. Dobermans were the 22nd-most popular dog breed in the United States last year.

"My research showed me they were among the smartest breeds, most loyal," Davis said.

The Doberman, however, is among the breeds whose popularity is declining, as are the chow chow, Akita and Pekingese.

And North Carolina's state dog, the Plott coonhound, is 142nd in popularity, 10th from the bottom on the kennel club's list.

The breed, which originated in the North Carolina mountains, has been recognized only recently by the kennel club. Herzog speculated that many Plott coonhound owners don't register their dogs.

The three most popular breeds in the United States last year were Labrador retrievers, golden retrievers and beagles.

And if you're wondering, Herzog does own a dog. Her name is Tsali, and (big surprise) she's a Lab.