From softpedia.com:

 Rocker Alice Cooper, annoyed by Paris Hilton and her Chihuahua, decided to make fun of her on his tour.

Cooper, 57, declared during an interview that, tired to see all the swanky pop singers with a chihuahua in their purse, decided to hire a Paris Hilton lookalike to fight with a little dog on stage, on his Dirty Diamonds tour, launched in America in August 2005. 

He says: “Is anybody not tired of seeing these divas with these little chihuahuas in their purse?  I said: ‘What would happen if one of the chihuahuas went for her throat and she’s on the floor beating this dog? The audience is dying laughing because everybody wants to see that!”