source: Phys.org

Dogs walked every day by their owners are less aggressive. Dogs owned by women bark less at strangers. Heavier dogs tend to be less disobedient than lighter pets. Pugs, Bulldogs, Shih Tzus and other short-snouted breeds may be more badly behaved than medium- and long-snouted dogs, such as Golden Retrievers or the caramel-colored mixed-breed dogs popular in Brazil. Read Full Article Here