At the Rockville Civic Center every kind of dog imaginable is trotting, crossing its legs to move sideways, spinning in circles and going through the handler’s legs — all in perfect time to everything from Bach’s Orchestral Suite No.1 in C to “Here Comes the Sun” by the Beatles.

The dogs — little mops, groomed-to-death poodles, herders, mutts — cut the rug better than lots of people. Some move to reggae, one to the theme from “Bonanza.” All stare at their owners entranced, as if they were looking at life-size beef treats — waiting intelligently for the signals on what to do next. They proudly shake their groove thing, all in exchange for a hug at the end. Of course, a few, like Polly (a cairn terrier and Toto lookalike), have had previous modeling and television experience. But still, it’s not that easy to move to “Mack the Knife.”

“The dog picks its music,” explains Joan Tennille, president of the Canine Freestyle Federation, speaking to about 70 spectators (which includes Adonis, an 8-month-old Cardigan Welsh corgi who is wearing an Easter bonnet, holes cut out for her ears.)

Why is it, Tennille is asked, that a dog might prefer a Jamaican steel drum tune to, say, Led Zeppelin?

“Dogs do know their music,” she says. “They have to trot to it, after all. And you’re really lucky when you get their tails moving on beat also.” She explains a certain glow, how the dog seems to get larger and stares at you. “You can’t miss it. They just say ‘That’s mine!'”

There are sentimental favorites, of course, like Ajax, a Shetland sheepdog who was rescued from life in a flea-infested stable by Edna Tusing. Ajax wouldn’t let anyone near him for the first year. Now, thanks to Tusing’s mind-boggling patience (2 « hours of training every Saturday, brush-ups every day), he makes it all the way through without a hitch and looks, if not confident, at least not freaked out.

And, of course, there are the naturals, gorgeous, intelligent dogs that jealous training-school dropouts can’t believe exist. Take the Level II first-place winner, Nicholas, a fluffy-tailed keeshond who only started practicing six months ago and kicks butt with his perky moves to Henry Mancini’s “The Elephant Walk.” His specialty is zigzagging through his owner’s legs as she walks.

Then there’s Wellington, a short-haired Saint Bernard who flatly refuses to budge. It seems reasonable. After all, just how much is a giant breed supposed to take? Life’s just too short to spend it doing what others ask of you, especially if you’re a Saint Bernard with a life expectancy of only eight to 10 years.

The music comes on. Nada from Wellington. Just drool, which has to be cleaned up before the next contestants can enter the ring. Even later, at the medal ceremony, he lies down like a slab of meat.

Maybe he didn’t like the song?

More likely the heat did him in, explains his owner, Michelle Koncilja, who sold her townhouse and bought property on 4 acres (with a pond) to accommodate Wellington. Wellington is sweet beyond belief, a show dog, and he does community work as a therapy dog, too. Heat, she says, is always a concern. She keeps her house at a crisp 60 degrees to help him feel well. When the temperature is over 95 degrees, she takes off from work to hose him down.

“This summer we’re going to Maine,” she says, packing up for the trip home to Stafford. “Mommy needs to get cool, too!”

Sure it’s over the top. But with any luck, canine freestyle will be back again next year, perhaps with Wellington in the running. Dogs, it has become obvious, love and need mental work, and they don’t much care what it is — even if it’s prancing to disco.

“We don’t do things to make the dog look silly or stupid,” says Ann Priddy, vice president of the Canine Freestyle Federation. “We honor and respect these animals.” S