Cut to the Chase People who wonder why dogs chase cars are missing the real question – what would a dog do if he caught the car?  Finding the answer will satisfy both questions. Dogs chase cars for the same reasons they chase kids on bikes, cats, small animals and other dogs:  They are either playing a game or they are hunting.  To a greater or lesser degree, chasing involves a dog’s natural prey drive.  If your dog is a herding breed, then your dog’s nature to herd the moving object is even greater. In most socialized, well-adjusted dogs, prey drive expresses itself as a canine tag game, in which the dogs take turns being “it.”  The object isn’t necessarily to catch the other dog; the real fun is just running around.  Chasing balls or Frisbees is another outlet for dogs’ prey drive. Dogs may play-fight as part of the game of tag, lunging or even snapping playfully at one another during the chase.  This form of play may extend to include cats, joggers, and people riding on bicycles or skateboards, or cars.  The intent is not to hurt or kill, but to engage the other creature (or thing) in a game.  Until you have learned to control your dog’s chasing instinct, do not let him off-leash.  It’s dangerous for him and the person or animal he is chasing. A more serious form of chasing is the hunt.  Some dogs have a higher prey drive than others.  Sporting, herding dogs, terriers, and hounds have enhanced prey drive; they have the potential to chase and kill their prey.  The sequence involves searching, stalking, chasing, catching, biting, killing and eating.  Such dangerous behavior is called predatory aggression, but it’s not a disorder and is not engaged in out of anger.  It’s a natural behavior that’s triggered by movement.  Predatory aggression has few warning signs and can be deadly to the victim.  If your dog shows a heightened prey drive, he should be under your control at all times.