And when that happens, a place long defined by its gambling and its growth will have a new distinction: it will become the first city in the nation to stop killing adoptable cats and dogs.

Shelter workers will unclasp small pins, in the shape of a paw, that they vowed to wear until there was a home for every animal. Mayor Jan Jones will rejoice.

``It will show what I've always believed about Las Vegas,'' says Jones. ``We're on the cutting edge of everything visionary. And no one expects it of us.''

In a country that kills an estimated 10 million dogs and cats each year, including 2 million purebreds, advocates hope the steps Las Vegas has taken to toward zero-euthanasia at its pound will be copied by communities nationwide. And they say what the city has done is all the more impressive because it's happening as Las Vegas' human and pet population explodes -- up 46%, to nearly 377,000 residents, since the 1990s began.

``This raises the bar and gives the rest of the communities in the U.S. something to strive for,'' says Wayne Pacelle, senior vice-president of the Humane Society of the United States. ``This will serve as a model community for other programs across the nation.''

Behind the breakthrough is an aggressive and energetic adoption program and, even more important, a high-volume, low-cost clinic -- initially financed by a gambling tycoon's largesse -- that spays and neuters 70 cats and dogs a day. That's more than anywhere else in the world.

The logic is this: Keep the animals from breeding and you won't have to spend money to kill their offspring. So even though 105 animals were brought to the shelter in just one day last week, Las Vegas is closing in on zero-euthanasia because it has spent the last nine years spaying and neutering every animal it could get its hands on.

Last year, 19,707 animals passed through the Las Vegas pound; just 615 ``adoptable'' dogs and cats had to be killed. Those were animals that were healthy and friendly, but the shelter ran out of space to keep them any longer (another 5,954 ``unadoptable'' animals -- diseased or vicious -- also were killed). So far this year, time has run out for 120 adoptable dogs and 240 adoptable cats.

``This is a big deal,'' says Mary Herro, Las Vegas' Animal Foundation president who turned the city around with a specific plan of preventing thoughtless breeding. ``Cities no longer have to pay to kill. It's where the hope is.''

And the savings. ``Prevention isn't only kinder,'' says Kim Sturla, director of companion animals for the Fund for Animals animal protection organization created by author Cleveland Amory. ``It's cheaper.''

Rounding up homeless animals, housing them, killing them and disposing of their bodies cost U.S. taxpayers an estimated $2 billion each year. In Houston, for example, it costs taxpayers $100 to kill an animal -- and $40 to fix it. The city kills 85,000 animals a year and has to truck 20 tons of dead cats and dogs to the city dump each week.

In many cities, the numbers of animals killed are staggering. Chicago destroyed 43,000 last year; New York, 45,000; Los Angeles, 55,000; San Antonio, 60,000. Generally, 30% of animals killed in shelters are considered unadoptable.

Advocates everywhere are trying to bring those numbers down. Breeding control legislation is on tap in 50 cities across the USA. Death-row animals may now be adopted over the Internet. And free spay-neuter vans are turning up in places likes Houston, where the NBA's Houston Rockets sponsor one.

The Las Vegas story begins in 1989, when Herro rescued a dog that had fallen out of a pickup truck onto the highway. The dog escaped injury but Herro wasn't sure how to get him back to his owner.

So she took him to the pound. ``I saw all those animals, looked in their eyes. It was too much,'' she says.

Herro, then semi-retired from her real estate career, had no experience running a shelter. But she was certain she could do better by the city's animals. She stayed up all night writing a proposal to the city council.

Her plan for a high-volume, low-cost spay-neuter clinic became reality with a $500,000 donation from Sahara casino owner William Bennett. In March, nine years after the clinic opened its doors, the Animal Foundation fixed its 100,000th animal, a boxer named Foxy. The city threw her a party.

All this is happening in a small, 7,500-square foot shelter and on a $1.2 million budget. Half the money comes from the city; half is from clinic fees ranging from $10 to neuter a male cat to $40 to spay a large female dog.

``If we don't have to kill in these horrible conditions, no city has to,'' says Herro.

There are an estimated 700 no-kill shelters in the United States, but what makes Las Vegas unique is that it aims to become a no-kill city.

It's a key distinction: city shelters must accept every animal that comes through the doors. Private no-kill shelters, on the other hand, have the option of taking only the most adoptable animals, leaving the city pounds with the job of killing animals that, while friendly and healthy, are a tough sell on the adoption circuit.

In Las Vegas, every adoptable animal will live, no matter how old, no matter how ugly.

So far, programs modeled after Las Vegas' have opened in Dallas, New York and Phoenix, and Herro has sent out 750 manuals on how to start similar high-volume clinics.

In Las Vegas, surgeries take place during four 10-hour shifts each week by Dr. Paul Chapin, one technician and three assistants. Animals are prepped and lined up on three operating tables. Chapin spends five to 15 minutes on each.

By the end of the day, the animals are lined up on blankets on the floor. Those with owners return home that night. The homeless cats and dogs return to the shelter to await adoption.

Spurred by the success, Herro is raising money to build a new $4 million shelter across the street that will be financed by city and private funding. Ground has been broken and she's already come up with $1 million and expects to raise the rest by the end of the year. The day the new shelter opens, she guarantees a home for every adoptable cat and dog.

The new shelter will be five times larger than the old building. And that 35,000 square feet, Herro says, will buy time for those animals still awaiting adoption.

The added space also will lead to less overcrowding, a main reasons shelter animals become ill. Because they are infectious, sick animals usually are killed.

Even without the bigger shelter, Las Vegas has done better by its shelter animals than most other cities.

Here, animals get 30 days at the shelter before their time is up. That's significantly longer than the three-to-five days most shelters nationwide keep animals around for before killing them.

A marketing approach has dramatically increased adoptions.

From 1995 to 1997, adoption rates rose from 14% to 44%. At an adopt-a-thon at the Hard Rock Cafe, 248 animals were adopted in four hours. That included a dog many shelters would reject: a friendly three-legged pit bull. Death row animals wore signs that said: ``This is my last day on earth.''

Herro also figured out a way to save animals that are too young to be adopted. In most shelters, puppies and kittens under eight weeks old are killed immediately because there isn't the staff or resources to care for animals that aren't old enough to eat on their own.

Instead, she created a vast foster home network that has 400 underage puppies and kittens at a given time. Foster homes care for the animals until they are old enough to be formally adopted. It's also a city ordinance that every animal that leaves the shelter must be fixed before it's adopted. The earliest that can happen is eight weeks.

Other innovations in Las Vegas: free weekly obedience classes, free spay-neuter of feral, or wild, cats, adoptions seven days a week, mobile vans delivering animals to PetsMart adoptions, reduced adoption fees for animals that are considered less-adoptable and waiving impound fees for low-income families who instead watch a film about responsible animal care.

``The public isn't aware,'' says Mayor Jones. ``Watch how fast mayors in other cities get energized when all of a sudden people say: What are you doing with our animals?'' What Las Vegas is doing now, by breaking the endless cycle of uncontrolled breeding -- is the only way to take charge of the situation, she says.

``What we're doing makes sense. It's cost-effective. It's humane. It sends the right message to our children and community.''