An off-duty Melrose firefighter rescued a teenager and a dog from a burning home Monday afternoon in Peabody.Rob McVoy, 36, was off-duty when he noticed the fire at 4 Broad St., according to reports. McVoy said he called the Peabody Fire Department and then rushed inside the home to find a teenage boy and his dog. The boy, his dog and a cat were alone in the home at the time. The cat did not appear to survive.The Peabody Fire Department arrived and extinguished the flames that were predominantly on the second floor of the single-family home. The home was heavily damaged by the blaze.McVoy has been a firefighter with Melrose for nine years.