The Fila Brasileiro (Portuguese pronunciation: [ˈfilɐ bɾaziˈlejɾu]) is a Brazilian breed of large working dog of mastiff type.

[1] In the eighteenth century, when slavery was still legal in Brazil, the Fila Brasileiro was used to return escaped slaves to their owners.

Dr. Paulo Santos Cruz began to systematically breed the Fila Brasileiro and also contributed to setting the CAFIB standard.

The ears are large, thick, tapered and either droop or fold back exposing the interior, depending on the dog's mood.

White markings, not exceeding 1/4 of the coat surface area, are permitted on the feet, the chest and the tip of the tail in the FCI standard.

[7][1][8] The standard imposed by the CBKC (a club affiliated to the FCI) is the most popular in the world, but it is by far the most distant from the appearance of the old dogs of four decades ago.

[7][6][9] This big difference between the three standards is mainly due to an accusation of a scandal of crossbreeding at the dogs registered by the CBKC in the 70's, 80's and 90's and, consequently, the many changes made in the CBKC standard probable to include dogs with characteristics of foreign breeds, such as the English Mastiff, Great Dane and Neapolitan Mastiff.

[6][1][7] Paulo Santos Cruz himself, who even participated in the formation of the CAFIB for these same reasons and even presided over the club, published an article in 1979 explaining how to differentiate a pure Fila from a mixed one.

[10][6] In Fiji,[11] the United Kingdom,[12] Norway,[13] Australia, Hong Kong[14] and Cyprus,[15] it is illegal to own any of these dogs without specific exemption from a court.