State legislators looking to improve protections for companion animals -- and the humans who buy them -- on Friday announced a bill designed to prohibit pet stores in DuPage and Will counties from selling dogs, cats and rabbits from commercial breeders.

The proposed law would make registered nonprofit animal control facilities, shelters and humane societies the only sources of dogs, cats and rabbits for stores in the two counties.

"This legislation will stop the cruel practice of breeding animals on a mass scale for retail sale in DuPage and Will counties, and that is really our objective here," said Rep. David Olsen of Downers Grove, who is sponsoring the bill in the state House.

The proposal modeled after a Chicago ordinance adopted in 2015, would apply only to pet store sourcing of dogs, cats and rabbits. It would impose a $500 fine on stores selling such animals from any source other than a 501(c)3 nonprofit animal control, shelter or humane society, said state Sen. Michael Connelly of Lisle, who is sponsoring the bill in his chamber.

The bill would not affect the sale of other animals and would not apply to breeders that supporters of the rule describe as responsible. These breeders often sell directly to customers after interviews and background checks, and under this proposal they could continue to do so.

"No reputable breeder sells their dog at a pet store," DuPage County Board member Brian Krajewski of Downers Grove said.

Officials speaking Friday at the Naperville Area Humane Society introduced the bill under the nickname Louie's Law. The moniker comes from a short-lived pet Goldendoodle that Keyonce Barrett of Naperville and her family bought from a pet store.

Barrett said Louie the pup appeared healthy when she took him home. But five days later, he was so sick she had to take him to an emergency animal hospital. Veterinarians diagnosed Louie with pneumonia, kennel cough, a bacterial infection and a collapsed lung. He died within two weeks of the family's bringing him home.

"We couldn't even give him a full life of happiness and play and fun," Barrett said. "He just passed away, and we wish that we could have done more."

Animal activists such as Cari Meyers, who founded an advocacy group called The Puppy Mill Project, say stores that use commercial breeders sometimes sell animals in poor health, likely because of conditions at breeding facilities.

But shelters and animal control and humane groups, they say, have higher standards for animal care, quarters, health, feeding and socialization.

Lawmakers who introduced Louie's Law included an opt-out clause so municipalities could vote not to follow its provisions.

But the change would need to be made at the state level because DuPage and Will counties do not have home-rule authority. If the bill passes, sponsors say they hope it can become a model to expand to the rest of the state.

The idea has the support of the state's attorney's offices in both counties, with DuPage State's Attorney Robert Berlin saying it "will reduce the financial and emotional toll on DuPage County consumers who purchase mill-bred pets with latent physical and behavioral problems."

"It will boost placement of shelter pets and it will reduce the county's animal care and euthanization costs," Berlin said. "This legislation is a win for taxpayers."