Worlds largest dog breed
The world's largest dog breed is the Mastiff. The dog has an average weight of 343lbs and it has a height of 8 feet from the nose to the tail. You can get more large breeds on http://thehydrant.wordpress.com/2011/07/13/worldslargestbreeds/.
I think Great Dane.?
Bouvier is a largest, powerful, rugged looking dog
The great dane
Mastiff, great Dane, and Irish wolf hound