The Oct. 8 and Oct. 10 raids, in which authorities seized around 80 pets from their owners at three public housing projects in Barceloneta, stirred widespread anger.

Residents say many of the animals were later thrown off the 50-foot (15-metre) Paseo del Indio highway bridge outside of town to their deaths.

"I'm here because we have to stop the abuse against dogs and other animals," said dog owner Mari Luz Santiago.

Fellow protester Ramon Martinez added: "If what they say is true, that's an action that's unfitting for any civilized country."

Mayor Sol Luis Fontanes ordered the raids after instituting a no-pet policy at the projects, though commonwealth and federal housing officials say they had no rules barring pets.

Forty-five residents filed a US$22.5 million federal lawsuit on Friday against the town, the Public Housing Administration, the owner of an animal control company and several others.

The suit claims at least 50 of the pets were beaten, drugged and then thrown to their deaths from the bridge.

Animal Control Solutions President Julio Diaz, whose company was contracted by the municipality, said municipal officials delivered the pets to his firm, which then euthanized the animals humanely.