First of all: Did I say the ca de bou is more "pure" than american bulldogs??? What i say is that ca de bous are dogs that have good temperament with family, can be excellent guardians and are very healthy dogs. And this conception is reafirmed by a lots of examples on the breed, here, in Puerto Rico. But with the AB, there are different lines. Johnson line, Scott lines, etc. and there can be a lot of differences between the lines, and within the lines.