Colleen Nicholson didn’t sense that anything was wrong when a woman and her five-year-old daughter came to visit. Not at first, anyway. They seemed like perfectly lovely people who wanted to buy one of the Doberman Pinscher puppies Nicholson had listed for sale. The pups were still too young to travel on that day, so the mother and daughter also spent plenty of time with Nicholson’s adult male Doberman, Magnum, and he loved them both. They seemed like the kind of people who would give a dog a great life—the only kind of people Nicholson ever allows to buy puppies from her Kelview Dobermans business in central Pennsylvania, where prices range from $2,400 to more than $3,500 per puppy.

“The puppies were six weeks old, and we hadn’t met her husband,” says Nicholson, whose sister works with her to ensure everything is in place before the puppies grow old enough to leave. “We want to meet everybody. She’d say, ‘Oh, he’s a surgeon, he’s busy,’ but we insisted. They came on a Friday night in separate cars because he was coming from the hospital. He got out of his Mercedes, and he was this little squatty guy, and his posture was just pure arrogance. We brought Magnum out—Magnum, who loves the world—and he stopped short and growled at him. We asked him to wash his hands, thinking maybe it was the antiseptic smell from the hospital, but it didn’t help. So now, our red flag is up. We trust Magnum’s instincts.

“I said, ‘I’m sorry, clearly something is wrong, so I’m going to give you back your deposit,’” Nicholson remembers saying.

The surgeon did not take her decision well.

“He started pacing back and forth and then he started shouting, ‘You can’t do this to me! I can buy whatever dog I want!’” she recalls. “Then I turned my back to get his check, which I hadn’t cashed, and he grabbed a lamp. The mother put the daughter behind her. She’d obviously seen that before. Magnum was by my side. If that guy had gotten any closer. . . .”

Nicholson’s sister called for help, including the police, but in short order the man stormed out and drove away. The family never contacted Nicholson again, but the surgeon did come up in conversation during the following months at regional dog shows.

“We heard he got a German Shepherd,” she says, shaking her head with disgust. “Somebody gave that guy a dog.”

As hard as it is to believe, the only thing standing between some of the highest-priced puppies in the world and whatever people want to do to them is often a single human being’s integrity. Nicholson is what’s known as a hobby breeder, which means a small-scale seller of dogs who maybe turn out one or two litters of puppies a year. Hobby breeders often describe themselves as people trying to better their breed, and they produce pet dogs as well as show dogs. Hobby breeders usually are involved with breed clubs and registries, they sometimes invest more money in testing for potential health problems than other breeders, and they generally are people who let their adult dogs live in their homes as members of their families, just as Nicholson did with Magnum. They often breed dogs as an income-generating hobby, just as the label implies. Nicholson, for one, earns her day-to-day living as a real-estate agent.

Legally speaking, though, a hobby breeder is no different than a backyard breeder, which is anybody who has a litter of puppies and offers them for sale. A backyard breeder might be somebody whose dog gets accidentally pregnant, or who sells a few litters of puppies each year with no desire to do anything but make a quick buck. In the eyes of most governments worldwide, hobby breeders and backyard breeders fall into the same category: noncommercial and unregulated. In America, breeders aren’t inspected by federal agents if they have fewer than four breeding females. The level at which legal regulation begins differs from nation to nation, but generally speaking, laws that regulate breeders are based on the notion that smaller is usually trustworthy. The US government says hobby breeders need no regulating because they “already provide sufficient care to their animals.” Frankly, nobody even knows who all the hobby and backyard breeders are, let alone where they are, so any inspectors trying to find them and regulate them would be utterly, hopelessly lost.

The lack of regulation means that standards vary wildly among small-scale breeders, which is how a lamp-wielding surgeon can get turned away by Nicholson while receiving a warm reception from a breeder of German Shepherds.

“A full-time breeder is not necessarily a professional,” Nicholson says. The governments of the world may think small breeders are generally more trustworthy, but she does not always agree.

“Never,” she says, pausing for emphasis, “never ever make assumptions.”

A utilities meter reader, sent to do an everyday house check on usage for May 2014, was the first person to notice the smell. It was wafting like invisible, toxic clouds from inside the house in Paoli, Indiana, a small suburb of Louisville, Kentucky.

The meter reader called the Orange County Sheriff’s Department, and Chief Deputy Josh Babcock arrived soon after. He and his fellow officers pulled air-purifying respirators over their faces to protect their noses and throats from burning in the putrid ammonia stench. They walked around the house, often not believing what they were seeing: two to three inches of feces in some places where dogs were walking. Kibble had been tossed atop the muck, though there was no water in bowls or anywhere else the pups inside the home could reach. Nine Poodles were packed into three cages, and another twelve Poodles were free to roam through the sludge. Some had maggots living in their skin, including under their eyelids. A veterinarian later shaved nine pounds of matted hair and feces from a single dog, with some of the clumps nearly the size of baseballs.

“In twenty years of law enforcement,” Babcock told reporters, “it’s one of the worst homes I’ve ever been into.”

Then came the truly shocking news from WLKY News, WBIB News, and WDRB News: The breeder charged with animal cruelty was named Laura King. Her references, if anyone buying a Poodle puppy from her had asked, could have included Metropolitan Veterinary Specialists in Louisville, where she worked as a veterinary technician during evening hours. Her colleagues found out about the charges only by seeing the story on the local news. They’d been aware she was a Poodle breeder, but nobody had ever visited the Paoli home. The people who knew King and worked with her—every last one of them an animal-care professional—said they were as stunned as everyone else to learn what appeared to be the horrific truth.

A lot of dog lovers trust people like vet techs, and might look to them and veterinarians first when it comes to locating a responsible breeder. Buyers think they’re up to speed because they’ve seen the commercials on television and the advertisements imploring everyone to be on the lookout for irresponsible breeders trying to make a fast buck by keeping hundreds of dogs at a time living in squalor. Nobody wants to support the so-called puppy mills, so dog lovers look for people selling dogs who seem small-scale and honest.

That may have been a reasonable practice in the past, but nowadays, the world’s worst small-scale breeders know it’s what the buyers are doing. Sellers are adapting their business practices and marketing stories accordingly. The least responsible are making themselves look an awful lot like the Colleen Nicholsons, to the point that buyers often can’t tell the difference.

The American Kennel Club and the Kennel Club in Britain each have inspection programs that purport to give buyers some kind of a legitimacy guarantee, but criticism reigns on both sides of the Atlantic about how few breeders the associations ever actually inspect. In 2013, the AKC acknowledged that it had no idea how many breeders in America owned AKC-registered dogs and that it had just nine inspectors covering the entire nation. Also in 2013, the Kennel Club released data in Britain showing it had inspected less than four percent of breeders admitted into its Assured Breeder Scheme that year, and that ninety percent of new breeders—nine out of ten—who had previously registered at least five litters of puppies, and who had been given the right to use the “Assured Breeder” label when talking with customers, had never been inspected at all.

Even breeders sanctioned by these groups as experts can turn out to be charlatans. In January 2013, the AKC reported that it had stripped the dog-show judge and Chihuahua breeder Margaret Ann Hamilton of all privileges for a decade. The action came after authorities in Washington State searched two homes and, according to the Seattle Post-Intelligencer and the Issaquah Press, found about a hundred dogs living in feces-covered stacked crates, walking in neurotic circles from constant confinement, and desperately in need of medical care, some so badly malnourished their jawbones were decomposed or gone.

What’s even scarier for consumers is that operators like King and Hamilton were reportedly working alone, or at most with the help of a spouse. In some parts of the world, animal-welfare advocates say this game of tricking purebred-puppy buyers has expanded not only across city and state lines but also national borders, and is now best described as multinational organized crime, or a “puppy mafia.”

“Not all of these are about mass breeding farms,” says Julie Sanders, the United Kingdom manager for Four Paws, an international animal charity with offices throughout Europe as well as in South Africa and the United States. “Some of them are about dealers in Eastern Europe having as many as three thousand breeders, and they are collecting from different breeders because they need puppies on the go at different times.”

Sanders, working with an undercover team posing as wholesale buyers, traced some of the puppies to one typical source: an animal market held every Sunday in Poland next to the regular market selling food, clothes, and other goods. She saw Chihuahuas, Miniature Pinschers, Staffordshire Terriers, Siberian Huskies, German Shepherds, Beagles, Maltese, Yorkshire Terriers, Spaniels, and more. The dog dealers were setting the sales quotas for the networks that transport the dogs to the deepest-pocket puppy buyers in Germany, the Netherlands, Spain, and Britain. The numbers of pups coming out of such places can be shocking; one dealer in Slovakia estimated that he alone distributed more than ten thousand dogs a year across Europe.

“It’s extremely sophisticated,” she says. “We were told when we were doing undercover filming at the puppy market that we had to buy more than ten puppies a month, and we were told to buy more because some would die en route—but not to worry because we’ll still make the money. They allow for a percentage over what you want, which is your wastage. It’s a stressful journey for puppies, from Poland to Europe to the UK. They may not be given food, water or anything.”

The puppies are distributed to private homes throughout Britain, with just a few offloaded at every stop where consumers will ultimately meet them. That way, they can be made to look like newborns from small-scale, individual breeders, advertised on the Internet to duped buyers.

“We’ve been told that some people try to purchase the breeds that match the dogs they have in the house, so people don’t ask questions,” she says. “Recently we were told they’re bringing the mothers over with the puppies because the puppies are so young, and so the mothers can be there to sell the puppies, then they bring them back to the puppy farms, which are horrendous.”

The reality for savvy, small-scale breeders or even networks of them today is that the law, or lack thereof, makes it easy to cut corners—and the fact that more and more people shop for dogs online provides a steady stream of customers to the worst offenders.

“As long as there is demand, there will always be suppliers,” Sanders says. “If there is money to be made, people will do it.”

Adapted from The Dog Merchants: Inside the Big Business of Breeders, Pet Stores, and Rescuers published by Pegasus Books.  Reprinted with permission. All other rights reserved.