The magazine for alumni and friends of Massey University.
Issue 14, April 2002

Why do dogs attack?

At the end of January 2003, seven-year-old Carolina Anderson was badly mauled by an American staffordshire dog while playing in an Auckland park. This was the first of a spate of dog attacks.

Quite simply we don’t know. One would need to have seen how the child, the dog and its owners behaved in the minutes before the attack, and one would need to know more about the dog’s background, specifically its breeding and training.

There is little information available on the background of dog attacks in New Zealand but international research suggests that the majority of dog attacks on humans occur at home with the victim a family member or visitor. This observation is supported by the stories reported in the media over the last two months, although in general dog attacks reported in the media are on strangers in public places.

Dog attacks on children in public places are more common in the summer or during weekends. Children under five are more likely to provoke dogs than older children, and the present thinking of many dog behaviour specialists is that when children behave erratically they provoke predatory behaviour in some dogs. Thus the dog that attacked Carolina may have responded as a predator to some aspect of her behaviour, but it is also possible that it was responding to something else, such as an unintentional behaviour of its owner. Running is known to trigger dog attacks, but the excitable behaviour and shrill squealing of young children may be interpreted by dogs as prey behaviour. Dogs that are used to children are less likely to attack and cause serious damage.

An analysis of children treated in A & E departments for dog bites found that the dogs involved were usually of the larger and more powerful breeds. Bites from pitbull terrier-type dogs are more often associated with serious injuries or fatalities. This is probably a consequence of the physical structure and abilities of these dogs, but is perhaps also influenced by the fact that these dogs may lunge, become airborne and injure the head and neck of the victims. The severity of injury influences the likelihood of its being treated and recorded and so there is a tendency for data to show large dog breeds as being involved in attacks. This does not prove that large dogs are more aggressive than small breeds, but that they are potentially more dangerous.

Dogs are social animals and attacks on family members are thought to be due to the dog being unsure of its status and using aggression to determine rank. This is generally why the majority of adults treated for dog bite injuries (75 percent) are injured by their own dogs. Dogs are also territorial: when visitors are bitten it is usually by dogs defending their territory. Posties and meter readers are often the victims of territorially aggressive dogs.

Attacks on strangers in public places may be predatory, may be due to fear, or may be a trained response. The trained response is often unintentional but aggressive behaviour may be encouraged inadvertently by the owner. A dog attack is the culmination of the dog’s breeding, its experience and training, and the circumstances immediately before the attack. The severity of the attack is influenced by the dog’s size and ability to injure and the size and ability of the victim. Thus when dog attacks become an issue of public concern, powerful dogs and small children are usually involved.

Karen Overall, a leading American dog behaviour specialist, recently reviewed the literature on dog attacks and concluded that the breeds most represented in dog bite data (1) vary over time, (2) are popular and (3) are not in proportion to their actual population. In almost all studies mongrels are the most common type of dog involved in attacks on humans. The variation in breed over time suggests that if specific dog breeds are legislated against, then another breed or type will be developed to meet demand for aggressive canines.

In the late 1980s a list of breeds involved in 40 serious dogs attacks on children in Adelaide included German shepherd dogs (10), German shepherd crossbreds (5), rottweilers (7), pitbull terrier-type dogs (4), Siberian huskies (3) and one akita, doberman pinscher, labrador retriever, chow chow and Australian shepherd. Pitbull terrier-type dogs have been involved in many of the recently reported dog attacks and are the target for those promoting breed control legislation. But dog aggression was a public problem in New Zealand before this type of terrier became common and some of the breeds listed above may come under scrutiny in the near future. In a 1995 study of veterinary opinion in New Zealand, rottweilers were considered much more aggressive in the veterinary clinic than any other breed of dog. Intact male dogs are also much more likely to be involved in dog attacks than females or desexed animals.

Protecting the public from dangerous dogs requires good legislation that is enforced, and public support. Many of the attacks that have occurred in the past few months could have been avoided if the 1996 Dog Control Act and local by-laws were enforced, and if people were willing to report inappropriate behaviour in dogs. Dogs were not supposed to be let off the lead in the park where Carolina was attacked. However, maintaining effective animal control services is expensive and enforcing breed control legislation, if it comes about, will also be costly. Local councils will expect dog owners to pay for animal control. Regardless of changes to the legislation, dog owners can expect a significant increase in dog registration fees in the future as councils attempt to improve dog control to reduce the risk of attacks such as that on Carolina. Dog ownership may easily change from a right to a privilege.

Associate Professor Kevin Stafford
Institute of Veterinary Animal and Biomedical Sciences.