The fact that dogs chase cats has been an enforced and sometimes unfair stereotype, as seen in cartoons depicting ongoing rivalries between the two household pets. Other times, dogs are simply seen as being overly dominant and aggressive, and would like nothing better than to bully an otherwise peaceful cat minding its own business. Getting to the root of the matter though, we can see that dogs chase cats for reasons grounded in evolution.

Dogs chase cats because they are natural predators. That is, before their domestication took place about ten thousand years ago, canines were acting upon survival instincts to chase and catch smaller creatures to eat. The survival instincts are also known as the "prey drive." While prey drive can be modified by training, the natural instinct that makes dogs chase cats is still triggered by movement.

When you throw a chew toy for your pet puppy, the puppy is essentially sent into cruise control mode when it rushes to chase, catch, and thrash the toy about in its mouth in order to "kill" its toy. This is because dogs are naturally programmed to chase moving animals. Similarly, dogs chase cats because the cat is moving around the household and in doing so, triggers the dog's prey drive. This is dangerous for pet owners though, because some medium to large-sized dogs can potentially kill cats if they can catch them. Most of the time however, well-fed dogs chase cats for the fun of it, although rough play can cause injuries to both animals.

Through selective breeding, people have been able to modify the prey drive, in order to breed dogs for performing certain functions. For example, border collies have been bred to herd sheep instead of mauling them in response to their movement. In dogs used by police to sniff out narcotics, the prey drive has been redirected toward objects instead of animals. The success of a catch and kill for dogs gives them an adrenaline high, reinforcing the behavior. Thus, to retrain the "dogs chase cats" instinct requires a massive investment of time, dedication, and management technique.