A pre-dawn fire in Bossier City has heavily damaged a house in the 4100 block of Parkway Drive and killed several dogs.  Investigators say it originated in a room behind the carport and appears to have been started by an electric space heater placed too close to a chair.  One of the home's human occupants was awakened just before 5:00am by the smell of smoke and managed to get the other three occupants out safely.  But nine dogs, most of them in cages in the room where the fire started, perished in the fire.