This article is from the Mastiffs Breed FAQ, by mmcbee@access.mountain.net (Mike McBee) with numerous contributions by others.
Not usually. A Mastiff of either sex tends to be stay-at-home
dog. Learning to stay within property boundaries comes
naturally. Some individuals, however, would put Houdini to
shame. Nevertheless, when your Mastiff is outdoors without
supervision, as with all breeds, it's a good idea to have him
in a secure, fenced enclosure.
 
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