A group dedicated to the preservation and promotion of the working Spanish Mastiff, this website is in Spanish, but a valuable resource.
Not all working Spanish Mastiffs are thin, lean and of little skin and bone, in spite of what some people claim. Even in Spain there are factions fighting over what is the "true" Mastin Espanol.
Further adding to the arguments out there, some of my best guardians have come from what are considered show lines. Heavier, loose skin - yet tenacious, protective and nurturing with my livestock. What too many people fail to take into consideration is HOW the dogs are raised. It is not all physical conformation that counts! What is in the dog's mind is just as important. You want stability, intelligence, perception and heart. Without these attributes, the dog is just a dog.