This old Portuguese breed shares its heritage with other Molossers of the Iberian region, especially with the Rafeiro de Alentejo, although the Rafeiro Montano shows greater eastern influence. These two workers were considered by be nothing more than regional types of the same breed in the past, but noticeable differences in appearance and personality between the two have served as the basis for their official separation. Like its Alentejo cousin, this breed is also seen by some as being very close to the original incarnation of the Spanish Mastiff. Rarely found outside Northern Portugal, the Cao de Gado Transmontano has been traditionaly used for driving livestock from the mountains to the valleys in the wintertime and back to the mountains in the summer. An impressive wolf killer and flock guardian, this is a very territorial breed, with little tolerance for strange dogs and people. However, the Transmontano Mastiff is friendly and calm around familiar faces and it gets along with other dogs belonging to its working pack, making this breed a valued and reliable shepherd's companion and protector. Loyal to its owner, the Transmontano Cattledog makes an excellent guard dog, but it's uncommon to see this breed in urban regions. In recent years a few specimens have been known to make appearances in Portuguese Dog Shows and the breed is slowly gaining popularity.
The Transmontano Mastiff is an intelligent, docile and obedient Molosser, although it can be overly independent and stubborn at times, needing early socialization and training. A very resilient and rugged dog, it is quite comfortable living outside. Long-legged, wide-chested and muscular, the Cao de Gado Transmontano is a fast and athletic working dog. The head is large and elegant, similar in type to some Asian and Turkish breeds. The neck is moderately long and well-muscled.
The coat is rich, densely undercoated and hard, coming in a variety of lengths and colours, but the medium-length coated white dogs with darker patches are the only ones considered pure by the breed authorities. Markings are commonly seen in black, fawn, brown, grey and brindle shades. Solid-coloured dogs are fairly common, but aren't as valued among the shepherds. The average height is 31 inches.