Dog Bite Injuries to the Face: Is There Risk with Breed Ownership? A Systematic Review with Meta-Analysis
A retrospective review of 240 pediatric patients, as well as a meta-analysis, showed that pit bulls and mixed-breeds pose the highest relative risk of biting and cause the most damage per bite.
- This study is a retrospective review of dog bite facial trauma cases from Nationwide Children's Hospital (NCH) and the University of Virginia Health System (UVA), two tertiary medical care centers with Level 1 trauma designations. Data was collected from 240 pediatric patients from 2002 to 2017. Bite risk by breed was created by a meta-analysis of literature from 1970 to current. "A composite measure was used to determine the severity of injury, and characterize each patient into an ordinal scale of bite severity. An average of each breed bite rate within each study was calculated and combined to create an empiric bite risk by breed." states the study.
- Bite Prevalence - Of the 26,000 bites reported in the meta-analysis, 39.9% were attributable to a specific breed and the others were either unknown or mixed breed. To equalize each study's breed bite prevalence, each study was broken down into percentage of bites by breed, these numbers then averaged across the 43 studies for each breed, the standard deviation calculated, and the breeds listed. "After this meta-analysis by breed, pit bulls were responsible for the highest percentage of reported bites across all the studies (22.5%) followed by mixed breed (21.2%), and German Shepherds (17.8%)," states the study. | See Figure 1
- Bite Severity - To assess bite severity by breed, the authors reviewed the cohort of 240 head and neck bites to determine the extent of injury in each case. An ordinal scale of bite severity was used. This ordinal scale was then averaged for each breed. The combined variables of bite risk and bite severity were then combined into a scatter plot by breed. Mixed breed and pit bulls were found to not only have the highest relative risk of biting, but were also found to have the highest average tissue damage per bite. Great danes and akitas were found to have a lower relative risk of biting, but the average damage from these bites were high. | See Figure 2
- Regional Risks - To show regional risk of dog ownership between the two institutions, the study also plotted the number of dog bites and breeds from the cohort of 240 bites by overlaying a bubble size on a bubble plot from each institution, plotted across "Increasing Bite Severity" and "Increasing Risk of Biting" axes. Notably, all of the dogs designated as "mixed-breed" and German shepherds came from one institution, NCH in Columbus, Ohio. The institution in Charlottesville, Virginia, UVA, reported zero for both.1 Breeds like the pit bull and akita were distributed evenly across the two institutions, the study reports. | See Figure 3
- Dog Morphology - This study also examined Dog Morphology (height, weight and dog head shape) as a way to group breeds by similarities. Dog breeds were assigned to characteristic head shape (dolichocephalic, brachycephalic, and mesocephalic) based on the "Cephalic Index." Results showed that canines with brachycephalic skull anatomy, as well as large dogs between 66 and 100 pounds, have an increased risk of biting as well as an increased risk for causing severe tissue damage. Pit bulls and mastiff-types are in this category. | See Figure 4
- "The purpose of this paper is to provide information to dog owners (or those considering ownership) about the types of dogs who may bite more frequently and/or cause more damage; with this information one can determine their risk tolerance for injury before an event occurs and potentially prevent a severe facial injury," the authors state. The authors of the study also recommend, "separating children from high-risk breeds and high-risk phenotypes reported in this study. Selecting for animals with low risk for biting and tissue damage may lower the risk injury."
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- This study does not state the percentage of breeds known in the cohort of 240 head and neck bites. It does state that within the meta-analysis of 26,000 bites, "39.9% were attributable to a specific breed and the remaining were either unknown or mixed breed." The bubble chart denotes that NCH had more breed data (and possibly more patients in the study) than UVA. Despite these limitations, given the long history of the German shepherd appearing in dog bite injury studies, it is unusual that UVA reported no facial trauma dog bite injuries by this breed during this 15-year period (2002 to 2017).