This article is from the Mastiffs Breed FAQ, by mmcbee@access.mountain.net (Mike McBee) with numerous contributions by others.
Puppies are puppies in most breeds. Young pups tend to bark
more than adults because of the excitement of play. Adults
rarely bark except when you first arrive home, or they hear a
sound they want you to investigate, like a doorbell. Most
Mastiffs will howl if they hear a siren close by, since it
sounds like a howl such as wild dogs would respond to.
 
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