Move over, Rover. Your time in the grocery store, the movie theater and pizza parlor is running out.

Twenty-one states have in recent months mounted a major crackdown down on people who falsely claim their pets as service and support animals so they can bring them into restaurants, theaters and other public places where Fido and Fluffy aren't typically allowed — and the movement has picked up speed in the last few weeks.

Last month, Minnesota Gov. Mark Dayton, a Democrat, signed into law a bill making it illegal for people to misrepresent their pets as service animals, under which pet-loving perps are subject to a $100 fine and a misdemeanor charge. Arizona Gov. Doug Ducey, a Republican, signed a nearly identical bill, under which those who "fraudulently misrepresent" service animals can be fined $250.

"I couldn't go into a store or an airport or even an office without seeing some disorderly four-legged creature dragging its owner around, wearing a vest that said 'service animal,'" Republican Arizona state Sen. John Kavanagh, who sponsored the Arizona bill, told NBC News. "I would see people in the supermarkets with animals in the shopping cart or walking around sniffing all the food."

Exactly how big a problem the use of fake service animals isn't clear. No organization keeps records of illegitimate service animals. But people who work in the service, hospitality and entertainment industries have seen it all.

A contingent of NEADS Service Dog teams and others gather to show support for House Bill 2277, an act relative to misrepresentation of service animals, outside of the Massachusetts State House in Boston on Sep. 12, 2017. David L. Ryan / Boston Globe via Getty Images

Andrew Hendrickson, a northern Vermont resident who volunteers regularly at a local performance venue, has seen it all too often.

"We've had dogs bark through the whole show, sit in the middle of the aisle,” said Hendrickson, who added that he once even saw one "hump the legs of a stranger."

The venue allows people to enter with animals they say are for service or support.

"It's kind of hard to question though," he said. "We have very little grounds on which to challenge a patron who claims the animal as a support."

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Animal and legal experts say that the explosion of reported problems is due to several factors.

There is no uniform nationwide certification or registration process for legitimate service animals — which receive up to several years of specialized training — making it easy for people to scam a non-existent system. And the easy availability online of "service dog" harnesses and vests is all too tempting for animal-owners who want company running errands and going out.

Most prominent, however, is that a new generation of animal-lovers are seeking notes from their doctors declaring that their pet helps soothe anxiety or ease depression and that the animals should be deemed "support animals." Support animals, however, don't qualify as service animals, according to the Americans with Disabilities Act — the governing law of all service animals, according to experts.

Under the ADA, only dogs can be considered service animals — with an exception for miniature horses.

Business owners, according to the federal law, can only ask two questions of anyone who says they have a service dog.

"They can ask only if it is a service animal, and what is it trained to do," explained David Favre, a law professor at Michigan State University’s College of Law, whose expertise is animal law. They cannot ask for documentation and they cannot ask about the disability, under the law, Favre said.

That makes abuses difficult to enforce.

More than 20 states have cracked down on those who falsely claim their pets as service animals so they can bring them on planes, or into stores, restaurants, theaters and other public places. Laura Fay / Getty Images

"Are business owners and restaurants really going to go after people who claim their dog is a service or support animal? If it has a vest of if the owner says it's helping them? They won't. They don't want to get sued," said Curt Decker, the executive director of the National Disability Rights Network.

Likewise, business owners don't want to delve into whether the animal is a "service" animal — protected under the ADA — or a "support" pet. Support animals are not protected under the ADA, with exceptions for those that comfort veterans suffering from Post-Traumatic Stress Disorder.

"It's compounded by the confusing terminology around this," said Amy McCullough, the national director of research and therapy programs at American Humane, an international animal rights nonprofit. "People prey upon that with the purpose of gaming the system."

The new laws largely do not apply to "support" animals, because businesses already have the legal right to turn away almost all of them.

But because most business owners won't risk a suit by asking about specifics, legislators and advocates are simply hoping that their laws will discourage support and service animal scammers.

"Keep some posters up...a few timely prosecutions and good media coverage of those could serve as a good deterrent and a good reminder that people shouldn't do this," said Decker, of the National Disability Rights Network.

The new state laws would likely crack down on people like David Chin, a visual designer from San Francisco. Chin said he visited a psychiatrist to get letters deeming his dogs, a four-year-old Cockapoo named Theo and a seven-year-old Bichon Frise named Bailey, as support animals that helped him with anxiety.

"None of the times was it for a true emotional need, it was for bending the system," Chin admitted, explaining that he enjoys being able to take his pups to otherwise restrictive patio restaurants and on airplanes.

It’s that kind of scenario that prompted Republican Minnesota state Rep. Steve Green to sponsor his state's recently passed bill. Green said he drafted the legislation after several disabled constituents told him that their own legitimate service dogs had been fatally attacked by other dogs whose owners had illegitimately claimed them as service dogs.

Meanwhile, cities and and airlines are trying to sniff out illicit service animals, too.

In February, a powerful Chicago alderman introduced an ordinance that would ban illegitimate service animals from the city's two main airports, and, since the start of the year, Delta and United Airlines both tightened the leash on guidelines for bringing support animals on plane rides — moves that state legislators pushing for crackdowns say will help their efforts.

"If you have a legitimate condition and the dog, or whatever animal, within reason, helps alleviate it, that’s great, this is America," said Kavanagh, the Arizona state senator. "But if you're just someone who needed to have Pookie around because you're upset when she’s not there, that is not okay."