Hundreds of pets decked out with sequins, ruffles and hats paraded on Rio's famed Copacabana beach Sunday in an annual pre-Carnival extravaganza briefly interrupted by a spate of robberies.

The annual "blocao," a play on the Portuguese words for "street party" and "dog," brought together dogs and their owners on the Copacabana promenade for a colorful concert of barks and samba accompanied by an unofficial contest for the best costume.

Among them were a chihuahua disguised as a peacock, a Cinderella poodle and a bulldog from the feared Rio police's Special Operations Battalion.

Veteran Franzao, a 16-year-old poodle, caused sensation with her leather boots, long dreadlocks and a hat with Jamaican colors in honor of Olodum, a famous samba-reggae ensemble from the northeastern city of Salvador.

"This parade is fantastic. It is an opportunity for our dogs to have fun with us," said the owner, 32-year-old Heluska Barroso from the southern tourist district of Ipanema, as she showed off her samba moves in front of a huge truck adorned with an enormous inflatable dog.

The vehicle slowly made its way down the avenue as a band perched on top belted out classic tunes such as "Marvelous City."

But suddenly pandemonium broke out amid shouts that thieves were around, prompting dozens of scared participants to flee.

The parade was interrupted and organizers called on police to eject the troublemakers.

"I have never seen anything like this in 11 years of blocao. About 20 people began to jostle, people with bad intentions. I grabbed my dog and protected it," Barroso said, adding that some arrests were made.

The parade later resumed though with much smaller crowds, after many participants left because of the incident and the heavy rain that followed.

But before leaving, a coquettish boxer named Melissa, her nails painted red and disguised as a ladybug, was among a few pets treated to a meat-tasting, non-alcoholic beer offered by an event sponsor.

"Everybody is entitled to have fun. The carnival is also for dogs," said Melissa's owner Vitor Aislan, a 24-year-old electrician.

Nearly 500 street parties are planned before and during the world-famous Rio Carnival, which officially kicks off Thursday.