Presa Canario teethThe conclusions that we draw about dangerous canines is derived from what we know about them. Our information primarily comes from our own random experiences, accounts of friends and family, and what we pick up from our culture. Norman Rockwell, the movie "Ferris Beuller's Day Off," and countless works of entertainment have presented dog attacks as being prosaic or even great fun. Less often, we are exposed to media accounts, governmental studies, lawmakers' arguments, reports from organizations such as the Centers for Disease Control, and the opinions of experts who have conducted original research.

Unfortunately, however, there are serious gaps in the data on this subject, leaving many of our assumptions and conclusions open to doubt. One of the most serious deficiencies pertains to the nature of the particular attack, meaning whether it was an angry assault, a playful turn of the head that resulted in a tooth catching the victim's skin, or something in between. In some cases, we are more interested in vicious attacks and less interested in pure accidents. For example, we need accurate information about vicious attacks when we debate the issue of breed bans. There are times, however, when we may be more interested in pure accidents, such as when considering whether dogs should be permitted in day care centers and hair salons. The nature of the attack is an inherently difficult issue to study on a wide-scale basis. To do so requires the questioning of witnesses and an impartial evaluation that is free of bias. In other words, it requires that we study depositions and trials or attend other proceedings where testimony is taken, such as legislative committee hearings and "dog court" hearings. This is feasible but has not been attempted to date.

Another deficiency is the extent of the damage inflicted on the victim. In most cases, we need to know which dogs are associated with the greatest damage. Such information is of prime importance in the debate on breed bans, the legal definition of an "assistance animal," the crafting of fair housing regulations on the federal and state level, and in similar matters. In some instances, however, we want to add up all of the scratches and nips too. There are people, such as parents, day care operators, dog park stewards and others, who need to compare a wide variety of characteristics of dogs, including whether a certain breed is more likely to scratch and nip.

The studies of fatal dog attacks or "canine homicides" are potentially most useful because they give us more details and focus on obviously serious injuries. Nevertheless, even these studies raise questions. Three commonly accepted sources of information about canine homicides are the CDC, Merritt Clifton (editor of Animal People), Colleen Lynn (author of dogsbite.org), and Karen Delise (author of Fatal Dog Attacks). However, none of their figures agree. This is largely because of the difficulties involved in gathering dog bite statistics. When the CDC reported on canine homicides, one of their methods of ensuring accuracy was to eliminate all death reports that did not appear in LexisNexis. When Delise did her study, she included all homicides which were confirmed in other reliable ways, such as by interviews and police files, and arrived at a figure that was 100 deaths higher than the CDC. Clifton's study includes both the USA and Canada, and is derived from newspaper accounts as well as his review of photographs and files. 

Delise illustrates the information problem in the following graphic way (quoted from her E-mail message sent to Attorney Kenneth Phillips):

Consider five fatal attacks included in the CDC statistics.

A man was bitten in the forearm by a Pit bull. The bite was not serious but introduced into the wound was a virulent and fast spreading bacteria. The man died 4 days later from this virulent bacterial infection.

A teenage girl give birth to a infant, distraught and frightened, she tossed the hours-old infant into a neighboring-junk-strewn yard where two Pit bulls resided. The dogs killed the newborn.

A German shepherd mixed breed dog went into a bedroom, lifted a newborn out of a crib and carried the infant (by the head) into the living room  where the adults were seated.

A man restrains his girlfriend, while ordering his Pit bull to repeatedly attack her.  He is eventually convicted of murder and is serving a 20-year sentence.

An elderly man attempts to stop his German Shepherd dog from fence fighting with his neighbor's dog, the dog turns on his owner, severely mauling him, inflicting fatal head and neck wounds.

The CDC was right, in that five people died as a result of a dog bite. But were all these bites the result of aggression? Were they the same type or level of aggression? Which behaviors initiated the attack, human or canine? So the number of deaths by dogs (as per the CDC) cannot be used to define aggression, or the aggression of certain breeds, as aggression is not defined or qualified.

The disagreement among experts, and the dearth of recent statistics, were two of the reasons why an appellate court for the State of Ohio ruled in 2006 that a pair of breed-based dangerous dog laws were unconstitutional (a court decision that later was reversed by the state supreme court). City of Toledo v. Tellings, 5th Dist. No. L-04-1224, 2006-Ohio-975 (Ohio App. 2006). The court of appeals began its analysis by noting:

Breed-specific laws were enacted because, in the past, courts and legislatures considered it to be a "well-known fact" that pit bulls are "unpredictable," "vicious" creatures owned only by "drug dealers, dog fighters, gang members," or other undesirable members of society. [Citing State v. Anderson (1991), 57 Ohio St.3d 168.] ... As scientific information advances and becomes available, courts have a duty to reconsider issues and make decisions which are supported by the actual evidence presented, instead of relying on "common knowledge" and opinion generated by newspaper sensationalism and hearsay, rather than accurate, scientific evidence. [Par.] As the evidence presented in this case demonstrates, previous cases involving "vicious dog" laws, especially from the late 1980's and early 1990's, relied on what is now outdated information which perpetuated a stereotypical image of pit bulls. ... The trial court noted that all the animal behaviorists from both parties testified that a pit bull, trained and properly socialized like other dogs, would not exhibit any more dangerous characteristics than any other breed of dog. After considering all the evidence before it, the trial court agreed, finding that pit bulls, as a breed, are not more dangerous than other breeds."

The court then stated that,

Our review of the record reveals no current statistics since 1996 were presented to support the notion that pit bulls have continued to be involved in a "disproportionate number" of attacks or fatalities. In our view, despite its own factual finding to the contrary, the trial court improperly relied on an outdated, irrelevant, and inadmissible source of factual information to revive the "vicious" pit bull sentiment and justify the finding that the statutes and ordinance are constitutional.

Even though not all bites are reported, victims don't necessarily know the breed that bit them, and we don't know exactly how many dogs of any one breed live in the USA, there have been studies by reputable agencies that identify biting dogs by breed and have great credibility. For example, animal control agencies and doctor groups have published their findings in some jurisdictions. These studies are not systematically collected. Many of them can be found on this website, however.