Fila brasileiro pups are deceptively sweet looking with their soft eyes, long ears and squinched up puppy noses. They can also be friendly to strangers for most of their first year, but more often than not they will begin to show some aversion to those outside their circle of friends and family as soon as they bond to the people in their new home. A fair percentage of fila pups show a marked dislike for anyone strange as young as eight weeks. This may manifest as moving away from the touch of a stranger to growling and actually making an attempt to bite if the person persists with their attentions.

Fila pups should be introduced to the family pets and livestock early, and of course the same applies to relatives and friends. It's always better to have the fila love your grandma than having to crate him or her (not grandma) while the person is around.

It goes without saying that you should introduce your pup to as many different experiences as possible while the puppy is still young, but this doesn't mean you take the dog out a few times and hope for the best forever afterwards. You need to make it an ongoing lesson to keep pushing the envelope of what the fila pup sees as normal and non threatening, ain small increments.

Don't push your pup too hard or punish him or her harshly for reacting aggressively. This breed was developed to have an aversion to strangers, you will NOT be able to train it out of them or change what hundreds of years of genetics is dictating. To do so can result in a very unhappy and unstable dog.

Alternatively, ongoing obedience training is a must. The fila brasileiro is a large strong and athletic breed, and nobody should have a disobedient, ill mannered dog regardless of breed. Your fila should be under your control at all times.

Occasionally you'll see people say that filas are exactly like any other guardian breed, and they only develop a dislike for strangers because  they are unsocialized. This is simply not true, as any breeder will tell you. You can have full siblings raised in the same family, exactly the same way and exposed to the same stimuli, only to have them turn out completely different around strangers.

You can find more info on the breed in the USA and a list of Fila Brasileiro Breeders in the USA at the Fila Brasileiro Association, the Fila Brasileiro Club of America websites.