DENVER - Candy normally keeps to herself and doesn't speak up. She stays close to those she knows best and does as she's told. When she dons her red handkerchief and hits the dance stage, though, she sheds her reserve.

To Brooks & Dunn's Boot Scootin' Boogie, she frolics, twirls and, as the country song instructs, does the "heel, toe, do-si-do."

Then she lands a slobbery lick on the face of her partner, owner MaryAnn Fuhrman.

Ms. Fuhrman and Candy, a 2-year-old white and fluffy Samoyed, are doing what's known as canine freestyle. In the growing sport, human and dog become a dancing duo, dress in over-the-top costumes and show off their fancy footwork using all six of their legs to songs of all genres, from country to disco to classical masterpieces.

The sport has invaded dog culture in America, including doggie day cares, kennels and boarding facilities. You can see it on YouTube.com and at places such as the National Western Stock Show, where Candy and roughly a dozen women and their dogs performed in front of about 100 cowboy hat-and-boot wearing spectators in January.

Dog owners and their pets don't cut the carpet just for exercise. Many try to perfect their routines to win competitions around the nation and worldwide. Colorado will be the site for two competitions this year being held by the World Canine Freestyle Organization, including the group's international titling contests that will take place in July.

The competitions are memorable.

At the stock show, one woman and her dog dressed in coordinating Denver Broncos gear (the woman in face paint), doing their dance as a tribute to murdered football player Darrent Williams. Another woman attired in red pranced around her toy poodle while Michael Bolton's Go the Distance blared from the speakers. During the routine, the woman did splits while her tiny dog jumped over her legs and circled around her.

At the end of the performances, the women changed into black, red, white, and blue sequined suits, grabbed American flags and did a choreographed dance to Shania Twain's Man! I Feel Like a Woman! and George M. Cohan's You're a Grand Old Flag, complete with a gigantic dog-and-human spinning pinwheel formation and chorus line of the owners kicking up their legs in unison.

"It's just pure fun. That is the crux of the thing. It's not a stress thing like a showing is," said Ms. Fuhrman, 62, of Lakewood, Colo., with Candy wagging her tail and standing by her side. "The dogs enjoy it as much as we (humans) do."

Ms. Fuhrman, like lots of canine freestyle dancers, first heard of the sport when she was putting her pets through obedience training. It's there, many say, where dog-human dancing got its beginnings in the late 1980s in Canada and Europe, when some people set their competitive obedience routines to music.

"Many people take credit for starting it, but no one has ever actually been called out," said Jessy Gabriel, the vice president of dog training at the Triple Crown Dog Academy in Austin, Texas, which specializes in dog obedience, training and agility.

Dog dancing clubs have sprouted around the nation, including the Mile High Musical Tails in Colorado, which has grown from five to 22 members since October 2002, said its founder and president, Sue Cianfarani.

Canine freestyle's popularity is rising in the United States, and the international scene is already big. It's especially popular in Australia, Holland, Japan and South Africa, said Patie Ventre, the founder of New-York based World Canine Freestyle Organization, which boasts 1,000 members and around 5,000 competitors in the events it holds annually.

She estimates around 15,000 people dance in clubs worldwide, which serve as gathering points for dog owners and the pets and a place where they can polish their dance moves.

In Great Britain, canine freestyle has become so popular that it is part of the program of the renowned Crufts Dog Show in England, said Kath Hardman, of Canine Freestyle GB.

"It is a serious sport in Europe," she said. "I don't think that those other countries are as advanced as the UK. But it won't take long. The sport is open to so many people, and since it's your own choice of music and 'dance,' anything's possible."

The pastime's simplicity and convenience for dog owners could be part of the reason for its popularity.

Skeptics often decide to give it a go after seeing a live performance, when they better understand how owners use verbal commands, eye contact and doggie treats to seduce their charges into twirling, walking through their owners' legs and doing low-height jumps.

Ms. Ventre said canine freestyle's low participation cost - man's best friend, a bag of treats and a creative imagination - and convenience that an owner and pooch can dance anytime, anywhere are high selling points, too.

"I just came home from work from teaching school, came in the door, and I'm teaching my dogs to dance right now, and I've got a smile on my face," Ms. Ventre said. "Anyone can do this."

Ms. Ventre said she had been developing canine freestyle into a competitive event when she started the World Canine Freestyle Organization in 1999. That included developing the scoring of performances, based on the technical and artistic aspects of the routine, and the guidelines for participants and judges, including making sure humans are performing with dogs they actually own and ensuring that the performance is original.

The organization's competitions have even been broken down to accommodate different skill levels, including junior, novice, intermediate and advance categories.

The organization, on its Web site, also sells training videos and books.

Ms. Ventre dreams about turning canine freestyle into an Olympic sport someday, but that goal is probably still pretty far off. If canine freestyle does make it into the Olympic arena, it would be making history. According to the International Olympic Committee's Web site, there are no Olympic sports that require canine competitors.

With the sport generally dominated by older women, the World Canine Freestyle Organization is hoping youths will continue the future of the sport. Ms. Ventre said it has been reaching out to 4-H clubs around America and has set up scholarships to send juniors to competitions around the world.

Shows such as January's National Western Stock Show give the dancers a chance to make contact with kids like Madeline McMillan, 8, of Aurora, Colo., who sat in front of the crowd of cowboys and cowgirls and vigilantly watched Candy twirl around her owner and hop on her back.

"I'm going to try to train my dogs to turn around when I get home," said Madeline, who has a 2-year-old dachshund and a 12-week-old golden retriever. "I'm going to tell my friends that I saw tons of dogs dancing - like they really could dance."