Simple SummaryAny dog is capable of biting, and dog bites can cause serious injuries to humans or other animals. To prevent dogs from biting, we need to understand the circumstances in which dog bites are most likely to occur. Once we have that information, we can act by improving public awareness and tailoring interventions to those most at risk of being injured. In this study, we assess the circumstances surrounding dog-bite injuries, by considering dog-bite severity in conjunction with information about where the incident occurred, about human victims, and about the dogs themselves. This approach was possible because The City of Calgary systematically tracks dog-bite severity. We found that from 2012–2017, the number of severe bites occurring in Calgary has fallen. That said, severe bites tended to occur in the homes where the dogs lived, and to be directed towards children and older adults. The results from our study underscore that educational communication for parents, grandparents, and other caregivers should emphasize the importance of constant supervision around dogs, including family dogs, whenever children are present. In addition, more attention should be paid to the risks that dogs pose to older adults. Failure to protect people from dog-bite injuries has implications for the dogs’ own welfare, as well as for human health. Dogs are most likely to bite when they feel insecure in the first place. Furthermore, common responses to severe dog-bite injuries in people include rehoming and euthanizing dogs.Dog bites are a public health concern that also implicates animal welfare, with negative outcomes such as rehoming or euthanasia for the animals responsible. Previous research has shown that the severity of dog-bite injuries reflects multiple factors, including the degree of inhibition exhibited by dogs and how people behave towards dogs. This study utilizes an objective dog bite injury assessment tool: The Dunbar aggression scale. Trained officers employed by The City of Calgary systematically use the Dunbar scale whenever investigating dog-bite complaints. We analyzed The City of Calgary’s administrative data on confirmed dog-bite injuries in people, 2012–2017, with a multivariable generalized ordered logistic regression model. Severe dog-bite injuries occurred more frequently in the family home than in any other setting. Young children, youths and older adults were at higher risk of more serious bites than adults. There has been a decreasing trend in the probability of a high or medium severity bite, and an increasing trend in the probability of a low severity bite since 2012. These results indicate that greater public awareness regarding dog-bite injuries is needed. Consideration should be given to campaigns targeted towards different demographics, including older adults, to provide an understanding of dog behaviour and to emphasize the need to supervise children closely in the presence of all dogs at all times, including family dogs in the home environment. Given that dog-bite injuries are not just a public health issue, but also an animal welfare issue, we endorse One Health responses in educational campaigns, policy development, and professional practice.