Are certain dog breeds more dangerous than others?

Whether or not certain dog breeds are more dangerous than others has been the subject of considerable discussion among ethologists and veterinarians, especially with regard to the usefulness of breed-specific legislation as an attempt to protect a community’s citizens from dog attacks/bites.  Breed-specific legislation is based on the assumption that there are genetic differences among breeds with regard to their dangerousness/aggressiveness.  However, many veterinarians and ethologists oppose breed-specific legislation, arguing that the genetic make-up of an individual animal is only one of many components that may enhance its aggressiveness.

Factors that may influence the specific danger of a dog bite/attack imposed by an individual dog include (1) the temperament and (b) the body characteristics of a dog, (3) the individual personality of the dog owner, (4) the specific circumstances of a bite incident, and (5) the individual personality of the victim⁴.  Breed-specific legislation is based on the assumption that the first two criteria, characteristics of the animal itself, are the most important factors that influence the potential danger imposed by dogs.  If this was true, comprehensible differences in temperament and/or body characteristics among dog breeds would be expected.  For example, we would expect that all pit bull-type dogs differ significantly in their temperament from other breeds.

Just operationalizing the notion of temperament is complex.  The temperament of a dog is defined as the sum of all his inherited and acquired physical and psychological traits, characteristics and abilities, which determine, shape and regulate the dog’s responses to his environment³.  Experiments investigating temperament differences among breeds must be based on objective temperament evaluation, which proves extremely difficult, since the environment is a variable difficult to control and standardize.  This is also true for the investigation of specific temperament traits such as aggression⁴.

Aggressive behavior in dogs is a species-specific trait which is genetically firmly established, because it has been highly influenced by natural selection during evolution as well as by artificial selection through man (e.g., selecting for inter-specific aggression in most guarding breeds and so-called fighting dogs)².  However, the fact that the aggression level of members of certain breeds can be increased (or decreased) through artificial selection does not prove that aggression itself is a highly hereditary trait⁴.  In most cases, dogs that have been selected for high levels of aggression are raised in a very aggression-stimulating environment.  Unfortunately, the blame for aggressive behavior in these dogs is usually solely placed on their genetic make-up, while environmental factors are often ignored.  Environmental and learning effects however, are always superimposed upon genetic influences¹.  Thus, early isolation and neglect as pups (e.g., in so-called “puppy mills”), training to attack other dogs and humans, and a low-stimulus environment with inappropriate exercise are factors that “create” dogs with social deficits (i.e., lack of appropriate interdog communication) which have an unstable position in their group (unstable dog-owner relationship), and are hard to influence.  Aggression in these dogs is rather a symptom of a behavioral disorder than a regulative species-specific behavior¹.

The “dangerousness” of a particular breed is also often blamed on certain physical characteristics, which are generally easier to evaluate than temperament, since most of them can be measured.  They include parameters such as body weight and height, power, jaw strength, pain threshold, as well as age and sex of the dog.  Body weight, height and length are measurable parameters which vary immensely among breeds.  Power and speed also differ among breeds.  However, the power of a dog is not only based on his genetic make-up, but also depends on his training condition.  Jaw strength is another measurable parameter.  Although certain dog breeds such as rottweiler or American Pitbull Terrier have the reputation of stronger jaws than others, valuable scientific studies showing significant differences in jaw strength among breeds do not currently exist⁴.  It is obvious that a larger and more powerful dog can potentially do more harm than a smaller, weaker dog.  Even a friendly greeting behavior such as jumping up on a person can become a potentially dangerous situation, depending on the size of the dog.  It is a fallacy to assume that all members of large breeds are generally more dangerous than all members of small breeds.  It is not the breed of an individual dog that makes a situation dangerous, but rather the circumstances involved.

The sex of the dog is another body characteristic that plays an important factor in aggressive behavior.  It has been shown that a majority of dog bites is inflicted by intact young males⁵. Thus, intact male dogs are, independently from their breed, potentially more dangerous than female dogs. Other physical characteristic influencing a dogs the tendency toward aggression include a dog’s pain threshold, as well as the animal’s age and overall health².  No valuable scientific method is currently available to objectively evaluate differences in pain tolerance among dog breeds⁴.  Health conditions that may elicit aggressive behavior can occur in all breeds and do not justify indiscrimination of certain dog breeds.

In summary, “the classification of dog breeds with respect to their relative danger to humans makes no sense, as both, the complex antecedent conditions in which aggressive behavior occurs, and its ramifying consequences in the individual dog’s ecological and social environment are not considered”¹.

Dr. Cornelia Wagner, DVM, MS                                                October 18, 2001

References

¹Feddersen-Petersen, D. U. (2001): Zur Biologie der Aggression des Hundes. Dtsch. Tierärztl. Wschr. 108 (3), 94-101.

²Lockwood, R. (1995): The ethology and epidemiology of canine aggression. In: Serpell, J. (ed.) The domestic dog: its evolution, behaviour and interactions with people. Cambridge University Press, Cambridge, UK.

³Seiferle, E. (1972): Wesensgrundlagen und Wesensprüfung des Hundes. Cited in: Feddersen-Petersen, D. U. (1992) Hunde und ihre Menschen. Frankh-Kosmos, Stuttgart, Germany.

⁴Stur, I. (2000): Zur Frage der besonderen Gefährlichkeit von Hunden auf Grund der Zugehöhrigkeit zu bestimmten Rassen. http://www.hund-und-halter.de/arbeitspapiere/arbeitspapiere-uebersicht.html

⁵Wright, J. C. (1985): Severe attacks by dogs: characteristics of the dogs, the victims and the attack settings. Public-Health-Reports 100, 55-61.