Council member Chris Herndon proposed the measure, which he co-wrote with the help of Shira Hereld, the owner of a pit bull named Merry. A few years ago, Hereld says, she felt like she had to move to the Denver suburb of Arvada, where there is no ban on the breed. She watched the winning vote and told the Denver Post that she is “over the moon” about the outcome.

In Denver, the path to pit bull ownership will begin with a “breed-restricted license,” which registers the animal with the city and requires proof that the dog has been microchipped, vaccinated for rabies, and spayed or neutered.

After 36 months without a violation of the city’s animal safety policies, Denver Animal Protection may waive the need for a restricted license and allow owners to register their pit bulls under the same requirements of any other breed.

The new city policy also limits pet owners to two pit bulls per household. Owners must notify the city within eight hours if their pit bull bites or escapes. If the dog dies or the owner moves, the city must be alerted within 24 hours.

Organizations such as the American Veterinary Medical Association, the Centers for Disease Control and Prevention, the American Bar Association, the Humane Society of the United States, and the American Society for the Prevention of Cruelty to Animals have expressly opposed breed-specific legislation, according to a journal article for the AVMA.

Breed-restriction ordinances in cities across the country first gained popularity in the 1980s, when news reports maligned pit bulls as aggressive and threats to public safety, the AVMA reported. The first breed-specific ordinance in the United States was enacted in Hollywood, Fla., in 1980, but was reversed two years later when a judge ruled there was little evidence that pit bulls posed a greater threat than other dogs, the article said.

As of 2017, more than 900 U.S. cities had some form of breed-specific ordinance, the AVMA reported.

Experts from the CDC and the American Veterinary Society of Animal Behavior told the AVMA that accurately identifying a dog’s breed is difficult, which can make dog-bite data based on breed inaccurate or unreliable.

“Breed bans de-emphasize the importance of responsible pet ownership in preventing dog bite injuries, diverting attention and resources away from effective measures such as socialization and training, neutering of male dogs, and licensing and leash laws,” Kendall Houlihan, assistant director of the AVMA’s animal welfare division, told the Denver Post.

Still, there remains an influential movement to create and enforce breed-specific legislation across the country. That tension played out during the Denver vote and has divided residents there for years.

The city’s new ordinance builds in space for critical evaluation of the decision in two years, when animal control will assess dog data and other findings and present them to the council.

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