With its large and imposing appearance, the Pyrenean Mastiff is surprisingly a calm and placid dog breed. Since it was bred to guard livestock, it retains most of its protective instincts and will not hesitate to guard its family from threats. When at home, the Pyrenean Mastiff is quiet, docile and gets along well with children. However, care should be taken when this dog is around small children because of its large size. The Pyrenean Mastiff is not aggressive, although it's naturally wary of strangers, which makes it an excellent watchdog and guard dog.
Socialisation and training at a young age will help Pyrenean Mastiffs develop their confidence to become well-adjusted adult dogs. They are intelligent and desire to please its owners, so they are relatively easy to train. Since this is a working dog breed, they are most happy when they are given some work to do which is why they are willing to learn new things.
When socialised at an early age, they get along well with other dogs, but they will never back down from a fight when threatened. The Pyrenean Mastiff gets on well with the family cat especially one they have grown up with. However, since it has a high prey drive, it will think nothing of chasing neighbours' cats and smaller animals as fair game.