Beware of the Big Bad, er, What, Exactly?
A new study tries, but fails, to clarify what breeds of dogs are most dangerous.
Posted Jun 04, 2019
Those of us who love dogs—and we are multitudes—must never forget that alongside the happy times we spend with our canine companions, there are occasional problems too. Dogs are not nearly as dangerous as humans, but sometimes dogs do hurt people, and the people they most commonly harm are children.
The authors of a recent paper in the International Journal of Pediatric Otorhinolaryngology (that’s ear-nose-and-throat medicine to the rest of us) point out that wounds caused by dogs can be quite severe and require substantial reconstructive surgery. Garth Essig Jr. and his colleagues at the Nationwide Children’s Hospital in Columbus, OH, and the University of Virginia School of Medicine looked at 43 published research studies containing data about dog bites, as well as bite reports from their own two hospitals. In total they had access to data on medical treatment for 26,000 dog bites—possibly the largest survey of its kind ever attempted.
Dr. Essig and his colleagues want to provide people with useful information about which breeds of dogs are most dangerous. This could be extremely valuable for families considering adding canine companionship to their human pack. Unfortunately, the authors of this study made two serious errors in their analysis.
Their first mistake was to assume that people landing at an emergency room actually know what breed of dog bit them. In some cases, the victim would have been harmed by their own dog, a dog with a pedigree and papers and whose breed, therefore, is beyond suspicion. This is likely to be a pretty rare case, however.
Fewer than 1 percent of the dogs in the U.S. are registered as pedigree, pure-bred animals with the American Kennel Club. There may be a roughly equal number of pure-bred dogs not registered with the AKC (Verdon, 2010). The remaining 98 percent of the time, people are just guessing—and we have completed studies showing that even experts’ guesses about mixed-breed dogs are often wrong (Gunter et al. 2018). Consequently, for most of the 26,000 dog bites in this study, the breed identity is just a shot in the dark.
Essig and colleagues’ second error was to imagine that how often a dog breed appears in their hospital records of bites gives some clue as to how dangerous that dog is in the community at large.
To take one example: According to Essig and colleagues’ analysis, German shepherds are more dangerous than Rottweilers. They believe this because, of the bites they recorded, more were claimed to have been caused by German shepherds than by Rotties.
Unfortunately, it does not follow that because the number of bites from shepherds is greater than the number of Rottweiler bites, shepherds are more dangerous than Rottweilers. This is because we don’t know how many German shepherds and how many Rottweilers are living in the communities from which these physicians collected their data. Perhaps more people were bitten by German shepherds just because there are more German shepherds around to bite people.
Unfortunately, in the United States, where dog registration is not consistently enforced, it is impossible to know how many dogs of different breeds live among us. An excellent study was carried out in the Netherlands, where dog registration is universal. That study found that, although nearly twice as many people were bitten by German shepherds as by Rottweilers, since the Netherlands contains nearly four times as many German shepherds as Rottweilers, the actual risk to a person of being bitten by a Rottweiler is nearly double the risk of being bitten by a German shepherd (Cornelissen & Hopster, 2010). Without that knowledge of the numbers of dogs of different breeds living in a community, information about bite numbers is quite useless.
Essig and colleagues have taken on an enormously important issue. Scientists and physicians need to understand why, how, and when people get bitten by dogs. For dogs and people to live their best lives together, we need to not only accentuate the positive but also reduce the negative. Tragically, however, their analysis only adds noise to an already complex and confusing situation.
The best practical advice is to look past whatever guesses may have been made about a dog’s breed makeup. Don’t leave small children alone around unfamiliar dogs of any breed, and supervise interactions with the family dog. Whether the dog is yours or a stranger’s, dogs have teeth. Learn what a dog who has reached his limit looks like (which varies between dogs, just as it does with people). To live well together, individuals—whether of the same or different species—need to respect each other’s needs. Give dogs space to rest, to eat in peace, and freedom from any stimulation that pushes them past their limits. At the present state of the science, that’s the best advice for peaceful coexistence.
Thanks to Lisa Gunter, Ph.D., for assistance in compiling this post.
Cornelissen, J. M. R., & Hopster, H. (2010). Dog bites in The Netherlands: A study of victims, injuries, circumstances and aggressors to support evaluation of breed specific legislation. The Veterinary Journal, 186(3), 292–298. https://doi.org/10.1016/j.tvjl.2009.10.001
Essig Jr, G. F., Sheehan, C., Rikhi, S., Elmaraghy, C. A., & Christophel, J. J. (2019). Dog bite injuries to the face: Is there risk with breed ownership? A systematic review with meta-analysis. International Journal of Pediatric Otorhinolaryngology, 117, 182–188.
Gunter, L. M., Barber, R. T., & Wynne, C. D. L. (2018). A canine identity crisis: Genetic breed heritage testing of shelter dogs. PLOS ONE, 13(8), e0202633. https://doi.org/10.1371/journal.pone.0202633
Verdon, D. R. (n.d.). AKC registrations continue to decline. Retrieved May 23, 2019, from dvm360.com website: http://veterinarynews.dvm360.com/akc-registrations-continue-decline