A new study by University of Manitoba researchers found that fewer dog-bite injuries were recorded at Manitoba hospitals after breed-specific legislation (BSL) banning pit bull terrier-type dogs was introduced in Winnipeg in 1990. Winnipeg was the first Canadian city to enact such legislation and it was gradually implemented in other jurisdictions over the following years.

The study’s lead author, Malathi Raghavan, is a researcher in the U of M’s Faculty of Medicine, with an appointment at the department of community health sciences. She cautions that the results of the study do not prove cause-and-effect, but there is a significant and promising link between the law and dog-bite injuries.

The population-based study, published in the journal Injury Prevention, used data on dog-bite injury hospitalizations seen in Manitoba from 1984-2006. A total of 16 urban and rural jurisdictions with pit-bull bans were identified and hospitalization rates within these jurisdictions were compared with hospitalization rates in the rest of Manitoba. The findings show that at the provincial level, there was a significant reduction in dog-bite injury hospitalization rates from the period before BSL to the period after BSL.  In Winnipeg, the rate of dog-bite injury hospitalizations, relative to Brandon (a Manitoba jurisdiction most like Winnipeg but without BSL), was lower in the period after BSL than in the period before BSL in people of all ages.

The effectiveness of BSL in decreasing the incidence of dog-bite injury hospitalizations was more pronounced in younger people than in people of all ages. That is, for every hospitalization seen in Brandon in young people, 1.28 hospitalizations were seen in Winnipeg before BSL and 0.92 hospitalizations after BSL.

Raghavan points out that the study is not expected to have the final word in the debate on BSL, but she is hopeful her data will help enlighten the debate. Instead of focusing on bites of all severities, current research was done on bite injuries severe enough to require hospitalizations. This is one of the unique features of the study.

“All dogs bite but my understanding is that BSL is based on the assumption that certain breeds are more likely to cause more severe injuries. If this were the case, we should expect to see a decrease in rates of severe injuries in jurisdictions with BSL compared with jurisdictions without BSL. This was the basis for my research question and hospitalization is an indicator of the severity of the injury,” Raghavan said.

“To my surprise, the trends in our data suggest that there may be something here that we need to pay further attention to, perhaps using data from larger jurisdictions with bigger populations of dogs, including those from the banned breeds, and higher rates of dog-bite injury hospitalizations.”

Although a positive finding of this study, the overall dog-bite injury hospitalization rate in Manitoba is relatively low compared with those in countries such as the USA, Australia and New Zealand.

Long-term studies such as the present study have been rare in this area of research, but they are necessary as they allow time for the community’s dog-breed composition to change gradually after BSL is passed. Generally after BSL implementation, existing individuals in the breed are allowed to live out their lives. But long-term studies also have the potential to be influenced by several parallel, unmeasured changes.  To some extent, the effect of these unmeasured changes have been controlled by comparing rates in jurisdictions such as Winnipeg and Brandon which are similar in many respects but specifically different with respect to BSL. This comparative aspect is again another unique feature of the study.

The study’s co-authors include Patricia J. Martens, Dan Chateau, and Charles Burchill from the Manitoba Centre for Health Policy (MCHP). Research scientists and their collaborators at MCHP, a research unit at University of Manitoba, study health services, population and public health, and the social determinants of health using data from the entire population of Manitoba. Most of the research answers questions of interest to policy makers based on a formal association with Manitoba Health and input from other government departments.

A copy of the study can be found here.

For more information contact Sean Moore, Marketing Communications Office, University of Manitoba, 204-474-7963 (sean_moore@umanitoba.ca),

Or Dr. Malathi Raghavan, Faculty of Medicine, at 204-789-3686 (Malathi.raghavan@med.umanitoba.ca).