Replace Denver BSL

BSL Facts & Data

Why Does Breed-Neutral Legislation Work?

Breed-neutral legislation works because it regulates the actual research-based causes of dog bites, including spay-neuter status, chaining, socialization, care vs. neglect, and proper leashing.

Consider these relevant factors that cause dog bites:

  • More than 70% of dog bite cases involve unneutered males; unneutered males are 2.6x more likely to bite than a neutered dog

  • 97% of dogs involved in fatal dog attacks in 2006 were not spayed or neutered

  • A chained/tethered dog is 2.8x times more likely to bite than a dog who is not chained/tethered

  • 78% of dogs involved in fatal attacks in 2006 were not maintained as pets, but for guarding, image enhancement, fighting, or breeding

  • 84% of these dogs were abused or neglected, inhumanely controlled and contained, or allowed to interact with children unsupervised

Successful breed-neutral legislation includes provisions for:

  • Improved leash laws

  • Sliding-scale penalties for owners of problem dogs

  • Public education programs

  • Prohibition of chaining/tethering and unreasonable confinement

  • Stricter enforcement of animal cruelty and fighting laws

How Do We Know Breed-Neutral Legislation Works?

Castle Rock, CO: When Castle Rock did their research in preparation for the replacement of their BSL, officials contacted municipalities across the United States that had replaced their BSL with breed-neutral laws within the last 10 years to see what the results have been. 17 municipalities responded: not a single one regretted going breed-neutral.

Boulder, CO: Boulder has breed-neutral dog laws and sees significantly fewer dog bites per year than Denver. Boulder’s Animal Care and Control Manager understands that an aggressive-dog ordinance is far more effective than a breed ban – as she explains, “if a situation does occur, that owner needs to be held accountable.”
Portland, OR: In 1986, Portland city convened a task force of vets, health officials, animal-control officers, and animal behaviorists – the recommendations from this commission led to a breed-neutral program that allows animal control officers to take action against the owners of a dog displaying aggressive behaviors. Portland’s program has reduced the amount of repeat biters by 257%.
Calgary, Canada: Over the course of 20 years, Calgary saw a five-fold reduction in dog bites due to breed-neutral legislation that included strong licensing and enforcement, coupled with dog safety public education campaigns. They went from 10 bites/10,000 people to 2 bites/10,000 people. Currently, aggressive dog attacks are at the lowest level they have been in 25 years. Calgary’s dog bite-injury hospitalization rate is significantly lower than that of Winnipeg, a city which has had a breed ban in place since 1990.
St. Paul, MN: In 2007, St. Paul passed an ordinance that addressed reckless dog owners, and provided reduced-cost licenses for owners who spay/neuter their dogs. Within 1 year, bites fell by 12%.
Multnomah County, OR: In 1991, Multnomah County established a community-based, breed-neutral animal control program aimed at reducing dog bites by imposing strict regulations before serious injuries could occur. The county has since decreased repeat-dog bites by 60%. 

More cities successfully removing BSL

Castle Rock, Colorado

In May 2018, Castle Rock repealed its 26-year-old BSL. Town staff (including Animal Control Officers with combined 15 years of experience) conducted extensive research for a full year. Their research showed that 1) breed-specific bans present a number of challenges and are difficult to enforce and 2) animal behavior is a better indicator of potential to bite than breed.

Ontario, Canada

Although Ontario’s attorney general promised that breed specific legislation would mean fewer attacks by dangerous dogs, the total number of dog bites in Toronto has consistently risen since 2012, and in 2013 and 2014 reached their highest levels of the century – even as pit bulls and pit-bull-type dogs neared local extinction.

Alamosa, Iowa

After decades of BSL, Alamosa lifted breed-specific restrictions on pit bulls in 2018. As resident Chris Collins said, “[BSL] doesn’t eliminate pit bulls. It causes people to go into hiding and the dogs aren’t socialized and they’re not taken to vets and if you have that, that’s a problem for any dog.”

Cincinnati, OHIO

Like Denver, Cincinnati is a home-rule city that banned pit bulls even as Ohio was moving away from breed-specific legislation. However, in 2012, Cincinnati replaced its dangerous dog law to popular acclaim – as vice mayor Roxanne Qualls stated, “the Cincinnati legislation is not working” and BSL is simply “not based upon fact.”

QUebec, Canada

 In June 2018, Quebec scrapped its 2-year-old pit bull ban. The councilors and mayor agreed that “there is no scientific basis for legislating against a specific breed…what’s more, even if we did it, it’s very difficult to apply it.” In its stead, Quebec instituted stricter penalties for aggressive dogs, regardless of breed.

Des Moines, IOWA

 Des Moines’ dangerous dog ordinance automatically classifies all pit bull dogs as vicious – even though other breeds continue to have a higher bite rate. The Animal Rescue League of Iowa opposes breed-specific ordinances. The Animal Care and Control operations manager says, “If we really want to get to the root of the problem, I think it’s holding owners more responsible.”


Although Tamarac had a pit bull ban since 1985, it has been seriously discussing repeal since 2017 because the ban has been too difficult to enforce. The executive director of the Florida Animal Control Association says, “It is behavior, owner training, and abuse that lead to situations.” The southern regional director for the Humane Society adds, “Pit bull registries like what Tamarac had didn’t get at the problem.”

Tell us how you feel about Breed-Specific Legislation or share a story about BSL in your community.

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Using Breed To Predict Behavior Is A Myth


Valid scientific research consistently shows that there is no way to determine the likelihood of a dog to bite based on breed. Despite biased media reporting, commonly stigmatized breeds have not been shown to bite more often or more severely than other large-breed dogs. The assumptions surrounding stigmatized-breeds being more likely to bite have consistently been found to be “simply untrue and unsupported by now accepted scientific, genetic, medical, or canine behavior principles.”

One big problem is that there is no accurate data for the numbers of each breed currently residing in the United States – which means scientists have not been able to accurately determine whether certain breeds are inherently more dangerous, or instead whether a breed’s high population is making it appear that the breed is more dangerous. One of the most commonly-cited CDC papers on dog bites specifically states that the data from the study “cannot be used to infer any breed-specific risk” and instead encourages breed-neutral strategies to prevent dog bites.

Visual Identification Is Inaccurate

Study after study, dating from the 80s and 90s all the way to today, on visual identification of dog breeds have all shown the same conclusion – even experts in the field are incapable of correctly identifying dog breeds with even a 50% level of accuracy. In one 2013 study with nearly 6,000 participants, only 15% of dogs were correctly identified more than 70% of the time – even the predominant breed was only correctly identified by respondents 27% of the time. Worse, Animal control officers designated to do the visual assessment often have no formal training in breed assessment. The inaccuracy of visual identification by veterinarians, animal shelter staff, and other experts, makes sense, given that recent genetic studies showing that fewer than 1% of a dog’s genes control commonly identifiable morphological features of specific breeds. (For example, a genetically 50% German Shepherd dog could present without the size, coat color, muzzle length, or ear properties of a German Shepherd.)

This raises both constitutional and practical issues and leads to subjective and arbitrary enforcement of BSL.

Visual Identification Leads To Improper Statistics

Why is the inaccuracy of visual identification such a problem? The data behind estimates of injurious dogs is frequently based on owner/witness identification or identification of shelter staff. In other words, when dogs bite people or animals, the suspected breed of dog reported by witnesses is often listed in official bite reports – these reports are then used to collate data on which dogs bite more often.

Furthermore, in most cases of cities with breed bans, the ban is based on visual identification. Or, as the 2013 study authors explained:

“The disparities between visual and DNA identification of the breed composition of dogs and the low agreement among people who identify dogs raise questions concerning the accuracy of databases which supply demographic data on dog breeds, as well as the justification and ability to implement laws and private restrictions pertaining to dogs based on breed composition.”

And speaking of biased media reporting…

Biased Media Reporting Creates More False Statistics

Media coverage of dog-bite injuries has been shown to be more extensive and report the breed more frequently when witnesses are reporting pit-bull or other banned breeds. Both media and witnesses will often also mis-identify breeds involved in attacks based on their own stereotypes. The ASPCA has reported that news outlets show little or no interest on reporting dog attacks unless they involve “bully breeds,” according to animal control officers country-wide. The vast majority of 1980s-2000s statistical studies on fatal dog attacks rely on newspaper articles for breed identification, further compounding the problem.