– Chris Slavin was in an elevator a couple of years ago with Earle, her yellow lab service dog, sitting calmly beside her wheelchair. The doors opened and in walked a woman holding a purse. In it was a teacup poodle the color of apricots.

The doors closed just as the poodle spotted Earle. That’s when the trouble started. In an instant, the poodle leapt from the purse, flung himself at Earle, and clamped his teeth into the bigger dog’s snout, leaving Earle bleeding.

“As soon as this occurred the woman said the poodle was a service dog,” said Slavin, who has a severe spinal injury that requires use of the wheelchair. “She then said he wasn’t a service dog but an emotional support dog. Finally, she admitted he was a pet she just wanted to bring in the building with her.”

Incidents like that one in Reading, Mass., have spurred 19 states to enact laws cracking down on people who try to pass off their pets as service animals. The push has been gathering steam in recent years: Virginia implemented its new law in 2016, and Colorado followed suit this year. Massachusetts is now considering a similar proposal.

“Today, any pet owner can go online and buy a vest for a dog to pass it off as a service animal to gain access to restaurants, hotels and places of business,” said Republican state Rep. Kimberly Ferguson, who introduced the Massachusetts bill. “Their animals aren’t trained and end up misbehaving in these public places, which gives real service dogs a bad name.”

Service dogs, which are trained to perform tasks for a person with a disability, were first used by people with vision and hearing impairments. They are now also used by those who use wheelchairs or have other impairment in mobility, people who are prone to seizures or need to be alerted to medical conditions, like low blood sugar, and people with autism or mental illness. The American Humane Association, which promotes the welfare and safety of animals, says there are 20,000 service dogs working in the U.S.

Supporters of the new laws compare those misbehaving dog owners to people who acquire handicap signs so they can park in spaces intended for disabled people. The laws make it a misdemeanor to represent an untrained dog as a service animal, and usually come with fines of no more than $500 for an incident.

But because there is no certification or official registry of legitimate service dogs, there is no way to verify whether a dog has undergone the training to become a service animal.

That makes it hard to enforce the laws, said David Favre, a law professor at Michigan State University College of Law and editor of its Animal Legal and Historical Center website. He said he’s not aware of anyone who has been prosecuted for violating them.

Rather, he said, the laws are largely symbolic, and meant to educate dog owners as well as people who let pets into spaces where they don’t belong. “Maybe you can scare some people into being honest.”

Service dogs receive up to two years of training, which can cost more than $40,000. Before they are placed, their new owners are often required to live at the training center for a week or two to learn about caring and interacting with their dogs. The waiting time for a service dog is often two years or longer.

But anyone can go online and purchase for about $20 the types of vests that legitimate service dogs usually wear.

There’s another complication: the growing use of “emotional support dogs,” which are intended to provide comfort to those with anxiety or other emotional problems.