The Fila Brasileiro has its roots in many of the big, bold, more aggressive mastiffs. One glance shows the Mastiff, Bloodhound, and probably Cane Corso influence.
These imposing dogs were bred to track their prey (man or animal), grab it and hold it down until the people working the dog caught up. They are an older breed, some say the breed has been around in some form since the 1600s, when Europeans first moved to Brazil and started working huge ranches and plantations.
The Brazilian ranchers and farmers wanted dogs that could track and hold. Dogs with aggressive, wary temperaments were desired, dogs that knew one master only. These characteristics were considered the most critical by those early dog breeders. Keep in mind, the Fila was used to guard huge ranches and plantations. Hunting large game, such as jaguars and boars and catching runaway cattle was also on the job description. The Fila was also used to track and subdue runaway slaves.
Being protective was instilled in the Fila from the beginning, so that trait is now firmly set in the Fila's genetics The Portuguese word for their temperament is Ojeriza, which directly translated into English means dislike and distrust. The Fila truly will willingly die for their master.
Some of the very features that are the Fila's most important and distinctive qualities can also be to their detriment. For example, the Fila is known for unwavering loyalty and protectiveness of their owners.
But, if kids are playing too loudly or rough-housing, the Fila could mis-interpret the sounds of play as danger.
Also, if a medical emergency occurs and EMTs need access to the owner, the Fila must be restrained or crated. All family members should be aware of this predisposition and know what to do in the event of an emergency. Of course, this info is shared in the spirit of forewarned is forearmed. If it does not apply yo your Fila, all the better.
Are they worth it? Absolutely!