Many dogs have a natural instinct to chase something.  Those triggers are usually activated by some fast, unexpected movement, like a bicycle, a cat, or even a car.   All dogs, regardless of how sweet they can be, are capable of predatory aggression.  Training when he or she is young will help you to control this natural instinct.  Unfortunately, if they are successful at chasing down and killing their prey early in their lives, the habit can be extremely hard to break.  As evidenced by their wild canine cousins, wolves, dogs are predators.  Many generations of domestication, selective breeding, and training have dramatically reduced their predatory instincts. Continue Reading