Naming the “largest dog breed” is inexact, because it depends on what parameters we used to define size. The Great Dane and the Irish wolfhound are taller than the mastiff, but in terms of sheer mass, mastiffs take the cake. Its imposing size is this breed’s most defining trait. Mastiffs are broad, heavy dogs with enormous heads. An average adult mastiff weighs as much as an adult human, between 140-200 pounds.
Ciampanelli, P. (2015) 10 Cool Facts About English Mastiffs. Retrieved from http://mom.me/pets/dogs/19368-cool-facts-about-english-mastiffs/item/english-mastiff-dressed-/