This article is from the Mastiffs Breed FAQ, by mmcbee@access.mountain.net (Mike McBee) with numerous contributions by others.
As for chewing, puppies of any breed need to be given durable
toys that they know it is OK to chew. Any time you catch your
puppy chewing on anything except its own chew toys, take the
forbidden item away from it, and give it a chew toy, and
encourage the dog to chew on its own toy. Praise it when it
DOES chew on its own toy. Repeat as necessary (remember, we
told you these dogs are stubborn!)
 
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