3. Fila Brasileiro/Brazilian mastiff
The fila Brasileiro, also known as the Brazilian mastiff, is known around the world for its fierce loyalty and protective instincts. They are affectionate and loving with family, but even with lots of socialization and training, they can still perceive strange humans and animals as a threat. Their “fila” instincts make them excellent guard dogs, which is exactly what these dogs were bred to be, but they are ill-suited for most family homes.