The Estrela Mountain Dog (Portuguese: cão da Serra da Estrela) is a large breed of dog from the Estrela Mountains of Portugal bred to guard herds and homesteads. It is 'one of the oldest breeds in the Iberian Peninsula.' A large, athletic dog, the Estrela Mountain Dog is a formidable opponent for any predator. It is calm but fearless and will not hesitate to react to danger, making it an exceptional watchdog as well as an excellent guard dog. It is intelligent, loyal, faithful, and affectionate to those it knows but wary of those it does not. It is instinctively protective of any children in its family. It needs early and continued socialization to be trustworthy around small pets and other dogs. (Source: Wikipedia.org, CC BY-SA)