Please replace me with an appropriate stub from Category:Stubs after the expansion is released.
Mastiffs are a breed of canine found primarily in Gilneas. Several mobs that once used the hyena model have been updated to use the new mastiff model in Cataclysm, such as the various hounds employed by the Scarlet Crusade.
Mastiffs were changed to tamable in Cataclysm. Mastiffs are classified as dogs in-game. Players that start as a worgenhunter receive a mastiff as their first pet.