Unlike the original Fonnese Mastiff of Roman consul Mark Pomponio Matone which was rooted in old Sylvan, as well as Greek, Persian and Assyrian Molosser blood, this rare Sardinian breed is a result of crossing the Dogo Sardo with the Pastore Fonnese. The Mastino Fonnese is sometimes falsely labeled as the Dogo Sardo, creating some confusion when it comes to differentiating these Sardinian working breeds. Some fanciers of the Pastore Fonnese don't even recognize the Mastino Fonnese as a separate breed, but claim that it's simply a smooth-coated variety of the Sardinian Sheepdog breed. The true fanciers of the Dogo Sardo strongly oppose this view, as do the Mastino Fonnese enthusiasts. Some authorities see all three Sardinian dogs as simply working strains of a single Pastore Fonnese breed. However, the differences between them are so evident that they can't be ignored. The Mastino Fonnese is by no means a bully type dog like the Dogo Sardo, being a fairly typical short-haired shepherd dog, in appearance similar to some Portuguese and Spanish breeds.
Employed as a livestock guardian and property watchdog, the Mastino Fonnese is a driven and fierce Molosser, described as being "rough around the edges" by the breed fanciers, due to its natural wariness of strangers and unfriendly attitude towards other dogs. Completely devoted to a single master, this rugged shepherd dog makes an excellent watchdog and rural companion, but a small number of specimens can reportedly be also seen guarding estates in urban areas. Intelligent, athletic and protective, this is an impressive working breed. The body is well-boned and powerful, but this is a fairly light mastiff, valued for its agility and stamina. The head is somewhat rounded, with a strong muzzle and well-developed jaws.
The short coat is very thick and densely undercoated, always brindle in colour, often with white markings on the chest and feet. Average height is around 24 inches.