All dogs have some level of prey drive (the motivation to chase, catch and kill small furry or feathered creatures) because hunting and killing was a way of life for their ancestors and the means for their survival. Predatory aggression by dogs does not reflect a psychological problem and neither is the perpetrator vicious, malicious or vindictive.
Predation is a natural survival-related behavior that may sometimes alarm or disgust us. The entire predatory sequence involves searching, stalking, chasing, catching, biting, killing and then eating.
Predatory behavior is not preceded by a significant mood change or threatening gestures because either would be counter-productive to the objective – to catch and kill the prey. The absence of warning signs plus the fact that killing is the natural end point for the behavior makes it dangerous for target animals and prey facsimiles.
Many natural drives of dogs, including prey drive, have been modified by selective breeding practices. Thus, the level of prey drive varies between breed groups - even between breeds. In fact, four of the seven breed groups of dogs recognized by the American Kennel Club (sporting, herding, hound and terrier groups) have an enhanced prey drive.
Dogs with high prey drive have greater potential to pursue and perhaps kill any perceived prey species. Dogs that have been bred for herding and sporting activities have a high prey drive but may have also been bred for having "a soft mouth." Terriers have been bred for a pure, unadulterated prey drive in the process of honing their vermint chasing and killing skills.
One of the key factors that distinguish predatory aggression from other forms of aggression is that movement often triggers it. In the wild, this movement is in the form of running and escape attempts of a small critter that the dog has honed in on as his prey. In the domestic situation, joggers, skateboarders, cyclists, automobiles, people on bicycles and running children frequently awaken the dog's otherwise dormant predatory instincts.
The results of such cases of mistaken identity can range from annoying to painful and even life-threatening. Dogs in such prey mode display relatively little mood change. They may slink up on their prey and, when within range, launch an attack. They then accelerate towards their target, either nipping at heels or biting at calves or thighs, perhaps hanging on in an attempt to drag their prey to the ground. Sometimes other dogs will be drawn in to the attack displaying "packing" behaviour or "group" aggression. When the subject is a young child who is attempting to run away, the results can be disastrous.
