Walker, S.K., Powell, L. and Berliner, E.A., 2026. A Retrospective Study of Canine Outcomes and Length of Stay in a Midwestern Shelter Subject to Breed-Specific Legislation. Journal of Shelter Medicine and Community Animal Health, 5.
Summary and Analysis
This study is included because it is one of a very few that examine the effects of breed-specific legislation (BSL) on dogs living in shelters and the impact on shelter resources of such legislation Dogs labeled as restricted breeds experienced longer shelter stays and reduced adoption opportunities, even though the study institution found no evidence of any difference in warning and biting behaviors between dogs labeled as restricted breeds and the rest of the shelter population.
Key Findings
- Dogs identified as breeds restricted under breed-specific legislation (BSL) experienced longer shelter stays and lower adoption rates than dogs categorized as other breeds.
- After controlling for body size, dogs categorized as legislated breeds still waited significantly longer to be adopted.
- No significant difference was found in euthanasia for “aggression” between legislated and non-legislated dogs.
- Breed identification relied on visual assessment, a method known to be unreliable for determining breed ancestry in mixed-breed dogs.
- The results suggest that policy barriers affecting dogs labeled as “pit bull–type,” rather than demonstrable behavioral differences, likely contribute to poorer outcomes for these dogs in shelters. The analysis used shelter software records for dogs entering the facility during 2022.
Breed-specific legislation typically restricts ownership of certain breeds—most commonly dogs categorized as “pit bull–type”—with the goal of improving public safety. Previous research has failed to demonstrate that such policies reduce dog bite injuries. This study instead examined how BSL affects shelter outcomes and population management.
The research was conducted in a managed-admission municipal shelter serving a Midwestern U.S. city of approximately 123,000 residents. Local law prohibited ownership of pit bull–type dogs, defined as American Pit Bull Terriers, American Staffordshire Terriers, Staffordshire Bull Terriers, or dogs displaying the majority of physical traits associated with these breeds. Residents were not permitted to adopt such dogs within the jurisdiction, although owners could reclaim them if they agreed to remove the dog from the jurisdiction and shelters could transfer them to other communities where they were permitted.
Study Sample
The original dataset included 1,042 canine outcome records for dogs entering and leaving the shelter during one twelve month period. After excluding puppies under eight months of age, dogs in training programs, and duplicate records for animals with multiple outcomes, the final analytic dataset contained 764 individual dogs representing 86 primary breeds.
Of these dogs:
- 118 dogs (15.4%) were categorized as legislated breeds, primarily American Pit Bull Terriers and American Staffordshire Terriers.
- 646 dogs (84.6%) were categorized as non-legislated breeds, including dogs labeled retrievers, German shepherds, huskies, boxers, chihuahuas, cattle dogs, and mixed breeds.
Most dogs entered the shelter as strays (66.6%), with other intake sources including public-safety seizures by animal control, assistance to police or fire departments, owner surrenders, and returns after adoption.
Breed Identification
Breed designation in the shelter database was based on visual phenotypic assessment by shelter staff, a common practice in shelters but one that has been repeatedly shown in research to be unreliable for determining breed ancestry in mixed-breed dogs. Genetic studies have demonstrated that most dogs in U.S. shelters have complex mixed ancestry that cannot be accurately inferred from physical appearance alone. Thus it is reasonable to assume that most dogs in this population were of mixed breed ancestry, regardless of the labels assigned to them by shelter staff.
This limitation has important implications for interpreting the study results. Many dogs categorized as “pit bull–type” or as other breeds are likely mixed-breed animals whose ancestry cannot be accurately determined through visual inspection. Misclassification therefore likely occurs in both directions: some dogs labeled as legislated breeds may not have majority ancestry or even any ancestry from those breeds, while some categorized as non-legislated breeds may share restricted breed ancestry but lack the physical traits used for classification.
Because the same visual identification process was applied to all dogs entering the shelter, this limitation affects both groups in the dataset. In this context, the poorer outcomes observed for dogs labeled as legislated breeds are consistent with the interpretation that legal barriers imposed by BSL—rather than intrinsic differences among the dogs themselves—limit adoption opportunities. If breed labels were removed or unreliable, many dogs in both categories would likely appear similar to adopters based on appearance and behavior alone.
Methods
The study used a retrospective review of shelter software records covering January 1 through December 31, 2022. Data variables included breed designation, age, sex, weight, spay/neuter status, intake type, outcome type, and length of stay.
Possible outcomes included adoption, return to owner (RTO), transfer to another organization, euthanasia, and death in shelter care.
For dogs with multiple events during the study period, the authors distinguished between first outcome, final outcome, and total length of care. Statistical comparisons between groups were conducted using chi-square tests and Mann–Whitney U tests.
Because body size can influence adoption likelihood, the authors also analyzed a weight-matched subset of dogs weighing 14.1–30.6 kg, corresponding to the size range of most legislated dogs.
Outcomes
Across the full dataset, live outcomes (return to owner, adoption, or transfer) accounted for 88.9% of first outcomes. Return to owner was the most common outcome (48.6%), followed by adoption (36.5%). Euthanasia accounted for 10.5% of first outcomes.
Dogs categorized as legislated breeds were less likely to achieve live outcomes and more likely to experience euthanasia as a first outcome. However, when the analysis was restricted to the weight-matched subset controlling for body size, the difference in overall live versus non-live outcomes was no longer statistically significant.
Reasons for Euthanasia
Euthanasia in this population most commonly involved cases coded as “aggressive” behavior. The study found no statistically significant difference between legislated and non-legislated dogs in euthanasia attributed to aggression.
Length of Stay
Dogs labeled as legislated breeds experienced longer shelter stays before reaching an outcome.
Median LOS in the full dataset was:
- 13.1 days for legislated dogs
- 10.0 days for non-legislated dogs
As noted above, in the weight-matched subset, overall live versus non-live outcome differences were not statistically significant. However, legislated dogs waited substantially longer to be adopted, with a median adoption LOS of 57.1 days compared with 34.5 days for non-legislated dogs. This has implications not only for the dogs’ welfare, but for shelter capacity resources.
Return-to-owner outcomes also took longer for legislated dogs, likely reflecting additional steps required for owners to comply with legal restrictions.
Study Strengths and Limitations
Strengths
- Analysis of a complete year of shelter records from a municipal shelter operating under an active BSL ordinance.
- Use of a weight-matched subset to examine outcomes independent of body size.
- Detailed outcome coding allowing comparison of adoption, return-to-owner, and euthanasia outcomes.
Limitations
- Data from a single municipal shelter, limiting generalizability.
- Visual breed identification, which is known to be unreliable in mixed-breed dogs.
- Retrospective shelter records may contain incomplete or inconsistent data.
Relevance to Policy
Because breed identification in shelters relies on visual assessment and is often inaccurate, policies that depend on identifying dogs by breed or appearance affect large numbers of mixed-breed dogs. In practice, such policies can create placement barriers for dogs labeled as restricted breeds while increasing the operational demands on shelters attempting to secure live outcomes for these animals.
https://jsmcah.org/index.php/jasv/article/view/146
