[header] How to choose between female and male dogs [title] Learn about aggression levels. [step] There are a lot of sweeping generalizations about dog gender, some of which are only partially true. One of the most commonly-held beliefs about male dogs is that they're more likely to chase other dogs and that they are always more aggressive than females. 
While there is some truth to this, neutering your dog will dramatically reduce the likelihood of these incidents. [substeps] Male dogs are more likely to challenge other male dogs, and statistically they may be more likely to show some aggression towards humans.