September 30, 2018

Audience: Executive Leadership, Shelter/Rescue Staff & Volunteers, Veterinary Team

Organization: University of Denver
Investigator(s): Kevin Morris, Sloane Hawes, Devrim Ikizler, Justin Marceau, Katy Loughney and Philip Tedeschi
Grant Amount: $55,510
Project Type: Basic Research
Project Status: Research Complete

Project Summary

The University of Denver and Institute for Human-Animal Connection examined how the City and County of Denver's Breed-Specific Legislation (BSL) ordinance, Section 8-55, introduced in 1989, has impacted the economic and social systems of the Denver community. The breed ban cost the city millions of dollars to implement and defend but resulted only in inconclusive public safety outcomes. Moreover, the ban has disproportionately affected individuals in underserved communities.


To conduct a Social-Environmental Economic Impact Assessment (SEEIA) to evaluate how the City and County of Denver's BSL policy has impacted the economic and social systems of the Denver community.


This study was conducted by a multidisciplinary team that included experts in the fields of economics, business, social work, law, and research design. The team integrated research-based evidence, local data and the knowledge of stakeholders, particularly members of the affected communities.


  • In studying the public's perception, a majority (64.8%) of the 253 respondents reported thinking that BSL costs less than $250,000 per year.
  • An economic assessment of BSL showed that the City and County of Denver has spent at least $5.8 million on enforcing the legislation, not including millions of dollars lost on direct and indirect pet-care revenue. By the research team's estimates, the city of Denver has lost $3.7 million per year in grooming, boarding and medical care-related services, for a total of $107 million since BSL was enacted.
    - Additional expenses are accrued by the City and County of Denver for intake, enforcement, evaluation, euthanasia and court costs of BSL-dogs.
    - BSL related economic impact estimation is a very new area of research. The other study identified that includes costs for BSL enforcement was a task force study conducted in Prince George County, MD. BSL in the City and County of Denver is estimated to cost $750/dog, compared to BSL in Prince George County at $378/dog.
  • BSL in the City and County of Denver has resulted in an extended length of stay for pit bull type dogs (PBTDs) in the care of animal shelters and also places undue strain on transfer partnerships with shelters in surrounding communities.
  • An estimated $1 million has been spent by shelters in surrounding communities to care for the PBTDs that are transferred as a result of BSL in Denver.
  • When accounting for human population growth in Denver, there was a statistically significant decrease in number of all dogs per 1,000 residents at the end of the study period.
    - In 2017, there were 41 dogs in the care of Denver Animal Shelter under the 8-55 ordinance, as compared to over 120 in 2007 (see Figure 2 of full report).
  • Removal of specific breeds of dogs runs in opposition with existing research showing the benefits of pet-keeping and pet-care in and for a community's social health.
  • Found that disproportionate enforcement of BSL occurs in underserved communities and communities of color, perpetuating historic trends of discrimination and marginalization in the U.S. and negatively impacting social cohesion of these communities.
  • City and County of Denver has accrued only questionable improvements in public safety across a number of relevant metrics. A minority (24.6%) of Denver residents say BSL makes them "feel safer," a perception that may serve as the primary reason for policymakers to continue the ban.


Existing research shows that visually-based evaluation processes commonly used by animal shelters to assess the breed and behavior can be erroneous. A growing body of evidence shows that companion animals can act as social bridges between people and community, and that BSL appears to disproportionately affect individuals in underserved communities. While BSL is primarily an intervention for the presence of dangerous dogs in communities, policy makers may wish to consider the additional implications of enforcing BSL in underserved communities.

BSL has been in place in the City and County of Denver for over three decades, which presented challenges to measuring economic impact, including changes in data collection practices, variable definitions and other mitigating factors. The limited awareness of a typical resident around the true costs of enforcing such a policy may demonstrate the need for a more detailed assessment.

The breed-ban's prioritization of human public safety at the expense of the welfare of a specific breed of dog, particularly without a substantial impact on the former, represents a diversion from the components that contribute to a Humane Community. Furthermore, the decreasing number of 8-55 "holds" may indicate that the need for BSL is diminishing.

In conclusion, the authors recommend alternatives to BSL that will address the root causes of actual dog aggression, including: building the City and County of Denver's capacity to support residents in caring for their pets by identifying and expanding pet support infrastructure such as affordable and accessible veterinary and behavior services; implementing robust non-breed-specific dangerous dog laws that include opportunities for early pet education and intervention with at-risk individuals; and implementing evidence-based interventions for challenges to social cohesion and interpersonal and interspecies violence.

- Hawes, S.M., Ikizler, D., Loughney, K., Temple Barnes, A., Marceau, J., Tedeschi, P. and Morris, K.N. (2020). A quantitative study of Denver's Breed-Specific Legislation. Animal Law Review,26(2). 195-271.