Laika, a gene-edited pig, was named in honor of the first living creature to orbit the earth, a stray dog named Laika.

(Courtesy eGenesis)

Untold numbers of animals have contributed to science, in ways big and small. Studying cows and cowpox helped English doctor Edward Jenner create a smallpox vaccine; Ivan Pavlov's experiments on dogs' reactions to external stimuli heavily influenced modern behavioral psychology.

We have these five animals to thank for some of our most important scientific advancements, from space travel to better organ replacement options.

Scientists still work with rats, rabbits, and other mammals to test cosmetics and pharmaceuticals and to conduct infectious disease research. Most of these animals remain nameless and unknown to the public, but over the years, certain individuals have had an outsize effect. We have these five animals to thank for some of our most important scientific advancements, from space travel to better organ replacement options.


Laika was the first living creature ever to orbit the Earth. In October 1957, the Soviet Sputnik I ship had made history as the first man-made object sent into Earth's orbit; Premier Nikita Khrushchev was keen to gain another Space Race victory by sending up a canine cosmonaut.

Laika ("barker" in Russian), was a stray dog, reportedly a husky-spitz mix, recruited among several other female strays for the trip. Although the scientists put extensive work into preparing Laika and the other canine finalists—evaluating their reactions to air-pressure variations, training them to adapt to pelvic sanitation devices meant to contain waste, and eventually having them live in pressurized capsules for weeks—there was no expectation that the dog would return to Earth, and only one meal's worth of food was sent up with her.

Laika the dog, with a mockup of her space capsule.

(Wikimedia Commons)

Sputnik II, six times heavier than its predecessor, launched on November 3, 1957. Soviet broadcasts reported that Laika, fitted out with surgically implanted devices to monitor her heart rate, blood pressure, and breathing rates, survived until November 12; the spacecraft stayed in orbit for five more months, burning up when it re-entered the atmosphere.

At the time, the Sputnik II team reassured the world that Laika had died painlessly of oxygen deprivation. It was only decades later, in the 1990s, that Oleg Gazenko—one of the scientists and dog trainers assigned to the mission—revealed that Laika had died 5 to 7 hours after launch from a combination of heat and stress. The capsule had overheated, probably as a result of the rushed preparation; after the fourth orbit, the temperature inside Sputnik was over 90 degrees, and it's doubtful she could have survived much past that. "The more time passes, the more I'm sorry about it. We shouldn't have done it," Gazenko said. "We did not learn enough from the mission to justify the death of the dog."

Yet even the four or five orbits that Laika did complete were enough to spur scientists to press on in the effort to send a human into space.


Four years after Laika's ill-fated flight, a chimpanzee named Ham entered suborbital flight in the American Project Mercury MR-2 mission on January 31, 1961, becoming the first hominid in space—and unlike Laika, he returned to Earth, alive, after a 16-minute flight.

Even though Ham's flight was not destined for orbit, the spacecraft and booster used on his trip were the same combination intended for the first (human) American's trip later that year. If he came back unharmed, NASA's medical team would be prepared to okay astronaut Alan Shepard's flight.

Ham receives his well-deserved apple.

(Wikimedia Commons)

For approximately 18 months before liftoff, Ham was trained to perform simple tasks, like pushing levers, in response to visual and auditory cues. (If he failed, he received an electric shock; correct performance earned him a treat. Pavlov would have been pleased.)

At 37 pounds, Ham was also the heaviest animal to ever make it to space. His vital signs and movements were monitored from Earth, and after a light electric shock from the ground team reminded him of his tasks, he performed his lever-pushing just a bit slower than he had on Earth, verifying that motion would not be seriously impaired in space.

Less than three months after Ham returned to Earth, on April 12, 1961, Soviet cosmonaut Yuri Gagarin became the first human to complete an orbital flight; Shepard was close behind, successfully crewing the MR-3 mission on May 5. For his part, Ham "retired" to the National Zoo in Washington D.C. for 17 years, before being transferred to the North Carolina Zoological Park; he died of liver failure in 1983 at age 26. His grave is at the International Space Hall of Fame in New Mexico.


A western lowland gorilla born at the San Francisco Zoo, Hanabi-ko, or "Koko," became famous in the 1970s for her cognitive and communicative abilities. Psychologist Francine "Penny" Patterson, then a doctoral student at Stanford, chose Koko to work on a language research project, teaching her American Sign Language; by age four, Koko demonstrated the ability both to make up new words and to combine known words to express herself creatively, as opposed to simply mimicking her trainer.

Koko and Penny compare notes.

(Photographer: Ron Cohn/

Koko's work with Patterson reflected levels of cognition that were higher than non-human primates had previously been thought to have; by the end of her life, her language skills were roughly equivalent to a young child's, with a vocabulary of around 1,000 signs and the ability to understand 2,000 words of spoken English.

An especially impactful study in 2012 showed that Koko had learned to play the recorder, revealing an ability for voluntary breath control that scientists had previously thought was linked closely to speech and could only be developed by humans. Barbara J. King, a biological anthropologist, suggested that Koko's immersion in a human environment may have helped her develop such a skill, and that it might be misleading to consider similar abilities "innate" or lacking in either humans or non-human primates.

Koko's displays of emotions also fascinated the public, especially those that seemed to closely mirror humans': she cared for pet kittens; appeared on Mr. Rogers' Neighborhood and untied the host's shoes for him; acted playfully with Robin Williams during a visit from him, and later expressed grief when told about the comedian's death. Koko died in her sleep in June 2018, at age 46. Patterson continues to run The Gorilla Foundation, which is dedicated to using inter-species communication to motivate conservation efforts.


Dolly—named after country singer Dolly Parton—was the first mammal ever to be cloned from an adult somatic cell, using the process of nuclear transfer. She was born in 1996 as part of research by scientists Keith Campbell and Ian Wilmut of the University of Edinburgh.

Dolly the cloned sheep.

(Wikimedia Commons)

By taking a donor cell from an adult sheep's mammary gland, using it to replace the cell nucleus of an unfertilized, developing egg cell, and then bringing the resultant embryo to term, Campbell and Wilmut proved that even a mature cell (one that had developed to perform mammary gland functions) could revert to an embryonic state and go on to develop into any and all parts of a mammal.

Although cloned livestock are legal in the U.S.—the FDA approved the practice in 2008, after determining that there was no difference between the meat and milk of cattle, pigs, and goats—Dolly has had an even bigger impact on stem cell research. The successful test of nuclear transfer proved that it was possible to change a cell's gene expression by changing its nucleus.

Japanese stem cell biologist Shinya Yamanaka, inspired by the birth of Dolly, won the Nobel Prize in 2012 for his adaptation of the technique. He developed induced pluripotent stem cells (iPS cells) by chemically reverting mature cells back to an embryonic-like blank state that is highly desirable for disease research and treatment. This technique allows researchers to work with such stem cells without the ethically charged complication of having to destroy a human embryo in the process.


Named in honor of the dog who made it to space, the second science-famous Laika was a genetically engineered pig born in China in 2015 as a result of gene editing carried out by Cambridge, MA startup eGenesis and collaborators.* eGenesis aims to create pigs whose organs—hearts, kidneys, lungs, and more—are safe to transplant into people.

Laika the gene-edited pig.

(Courtesy eGenesis)

Using animal organs in humans (xenotransplantation) is tricky: the immune system is very good at recognizing interlopers, and the human body can start to reject an organ from another species in as little as five minutes. But pigs are otherwise exceptionally good potential donors for humans: their organs' sizes and functions are very similar, and their quick gestation and maturation make them attractive from an efficiency standpoint, given that twenty Americans die every day waiting for organ donors.

Perhaps unsurprisingly, Dolly the sheep helped move xenotransplantation forward. In the 1990s, immunologist David Sachs was able to use a similar cloning method to eliminate alpha-gal, an enzyme that is produced by most animals with immune systems, including pigs—but not humans. Since our immune systems don't recognize alpha-gal, attacks on that enzyme are a major cause of organ rejection. Sachs' experiments increased the survival time of pig organs in primates to weeks: a huge improvement, but not nearly enough for someone in need of a liver or heart.

The advent of CRISPR technology, and the ability to edit genes, has allowed another leap. In 2015, researchers at eGenesis used targeted gene-editing to eliminate the genes for porcine endogenous retroviruses from pig kidney cells. These viral elements are part of all pigs' genomes and pose a potentially high risk of infecting human cells. (After the HIV/AIDS crisis especially, there was a lot of anxiety about potentially introducing a new virus into the human population.)

The eGenesis lab used nuclear transfer to embed the edited nuclei into egg cells taken from a normal pig; and Laika was born months later—without the dangerous viral genes. eGenesis is now working to make the organs even more humanlike, with the goal of one day providing organs to every human patient in need.

*[Disclosure: In 2019, eGenesis received a series B investment from Leaps By Bayer, the funding sponsor of leapsmag. However, leapsmag is editorially independent of Bayer and is under no obligation to cover companies they invest in.]

[Correction, March 3, 2020: Laika the gene-edited pig was born in China, not Cambridge, and eGenesis is pursuing xenotransplant programs that include heart, kidney, and lung, but not skin, as originally written.]

Eleanor Hildebrandt
Eleanor Hildebrandt is a writer and researcher from Seattle. Her work has appeared in the Boston Review and Popular Mechanics. Follow her on Twitter at @ehhilde.

Claire Guest, co-founder of Medical Detection Dogs, with Daisy, whom she credits with saving her life.

(Photo credit: Darcie Judson)

Daisy wouldn't leave Claire Guest alone. Instead of joining Guest's other dogs for a run in the park, the golden retriever with the soulful eyes kept nudging Guest's chest, and stared at her intently, somehow hoping she'd get the message.

"I was incredibly lucky to be told by Daisy."

When Guest got home, she detected a tiny lump in one of her breasts. She dismissed it, but her sister, who is a family doctor, insisted she get it checked out.

That saved her life. A series of tests, including a biopsy and a mammogram, revealed the cyst was benign. But doctors discovered a tumor hidden deep inside her chest wall, an insidious malignancy that normally isn't detected until the cancer has rampaged out of control throughout the body. "My prognosis would have been very poor," says Guest, who is an animal behavioralist. "I was incredibly lucky to be told by Daisy."

Ironically, at the time, Guest was training hearing dogs for the deaf—alerting them to doorbells or phones--for a charitable foundation. But she had been working on a side project to harness dogs' exquisitely sensitive sense of smell to spot cancer at its earliest and most treatable stages. When Guest was diagnosed with cancer two decades ago, however, the use of dogs to detect diseases was in its infancy and scientific evidence was largely anecdotal.

In the years since, Guest and the British charitable foundation she co-founded with Dr. John Church in 2008, Medical Detection Dogs (MDD), has shown that dogs can be trained to detect odors that predict a looming medical crisis hours in advance, in the case of diabetes or epilepsy, as well as the presence of cancers.

In a proof of principle study published in the BMJ in 2004, they showed dogs had better than a 40 percent success rate in identifying bladder cancer, which was significantly better than random chance (14 percent). Subsequent research indicated dogs can detect odors down to parts per trillion, which is the equivalent of sniffing out a teaspoon of sugar in two Olympic size swimming pools (a million gallons).

American scientists are devising artificial noses that mimic dogs' sense of smell, so these potentially life-saving diagnostic tools are widely available.

But the problem is "dogs can't be scaled up"—it costs upwards of $25,000 to train them—"and you can't keep a trained dog in every oncology practice," says Guest.

The good news is that the pivotal 2004 BMJ paper caught the attention of two American scientists—Andreas Mershin, a physicist at MIT, and Wen-Yee Yee, a chemistry professor at The University of Texas at El Paso. They have joined Guest's quest to leverage canines' highly attuned olfactory systems and devise artificial noses that mimic dogs' sense of smell, so these potentially life-saving diagnostic tools are widely available.

"What we do know is that this is real," says Guest. "Anything that can improve diagnosis of cancer is something we ought to know about."

Dogs have routinely been used for centuries as trackers for hunting and more recently, for ferreting out bombs and bodies. Dogs like Daisy, who went on to become a star performer in Guest's pack of highly trained cancer detecting canines before her death in 2018, have shared a special bond with their human companions for thousands of years. But their vastly superior olfaction is the result of simple anatomy.

Humans possess about six million olfactory receptors—the antenna-like structures inside cell membranes in our nose that latch on to the molecules in the air when we inhale. In contrast, dogs have about 300 million of them and the brain region that analyzes smells is, proportionally, about 40 times greater than ours.

Research indicates that cancerous cells interfere with normal metabolic processes, prompting them to produce volatile organic compounds (VOCs), which enter the blood stream and are either exhaled in our breath or excreted in urine. Dogs can identify these VOCs in urine samples at the tiniest concentrations, 0.001 parts per million, and can be trained to identify the specific "odor fingerprint" of different cancers, although teaching them how to distinguish these signals from background odors is far more complicated than training them to detect drugs or explosives.

For the past fifteen years, Andreas Mershin of MIT has been grappling with this complexity in his quest to devise an artificial nose, which he calls the Nano-Nose, first as a military tool to spot land mines and IEDS, and more recently as a cancer detection tool that can be used in doctors' offices. The ultimate goal is to create an easy-to-use olfaction system powered by artificial intelligence that can fit inside of smartphones and can replicate dogs' ability to sniff out early signs of prostate cancer, which could eliminate a lot of painful and costly biopsies.

Andreas Mershin works on his artificial nose.


Trained canines have a better than 90 percent accuracy in spotting prostate cancer, which is normally difficult to detect. The current diagnostic, the prostate specific antigen test, which measures levels of certain immune system cells associated with prostate cancer, has about as much accuracy "as a coin toss," according to the scientist who discovered PSA. These false positives can lead to unnecessary and horrifically invasive biopsies to retrieve tissue samples.

So far, Mershin's prototype device has the same sensitivity as the dogs—and can detect odors at parts per trillion—but it still can't distinguish that cancer smell in individual human patients the way a dog can. "What we're trying to understand from the dogs is how they look at the data they are collecting so we can copy it," says Mershin. "We still have to make it intelligent enough to know what it is looking at—what we are lacking is artificial dog intelligence."

The intricate parts of the artificial nose are designed to fit inside a smartphone.

(Courtesy Mershin)

At UT El Paso, Wen-Yee Lee and her research team has used the canine olfactory system as a model for a new screening test for prostate cancer, which has a 92 percent accuracy in tests of urine samples and could be eventually developed as a kit similar to the home pregnancy test. "If dogs can do it, we can do it better," says Lee, whose husband was diagnosed with prostate cancer in 2005.

The UT scientists used samples from about 150 patients, and looked at about 9,000 compounds before they were able to zero in on the key VOCs that are released by prostate cancers—"it was like finding a needle in the haystack," says Lee. But a more reliable test that can also distinguish which cancers are more aggressive could help patients decide their best treatment options and avoid invasive procedures that can render them incontinent and impotent.

"This is much more accurate than the PSA—we were able to see a very distinct difference between people with prostate cancer and those without cancer," says Lee, who has been sharing her research with Guest and hopes to have the test on the market within the next few years.

In the meantime, Guest's foundation has drawn the approving attention of royal animal lovers: Camilla, the Duchess of Cornwall, is a patron, which opened up the charitable floodgates and helped legitimize MDD in the scientific community. Even Camilla's mother-in-law, Queen Elizabeth, has had a demonstration of these canny canines' unique abilities.

Claire Guest, and two of MDDs medical detection dogs, Jodie and Nimbus, meet with queen Elizabeth.

(Photo credit: Derek Pelling Photography)

"She actually held one of my [artificial] noses in her hand and asked really good questions, including things we hadn't thought of, like the range of how far away a dog can pick up the scent or if this can be used to screen for malaria," says Mershin. "I was floored by this curious 93-year-old lady. Half of humanity's deaths are from chronic diseases and what the dogs are showing is a whole new way of understanding holistic diseases of the system."

Linda Marsa
Linda Marsa is a contributing editor at Discover, a former Los Angeles Times reporter and author of Fevered: Why a Hotter Planet Will Harm Our Health and How We Can Save Ourselves (Rodale, 2013), which the New York Times called “gripping to read.” Her work has been anthologized in The Best American Science Writing, and she has written for numerous publications, including Newsweek, U.S. News & World Report, Nautilus, Men’s Journal, Playboy, Pacific Standard and Aeon.
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Cows on a pasture, who, among other mammals, could experience immense suffering from the New World screwworm.

(© Creaturart/Fotolia)

Combining CRISPR genome editing with the natural phenomenon of gene drive allows us to rewrite the genomes of wild organisms. The benefits of saving children from malaria by editing mosquitoes are obvious and much discussed, but humans aren't the only creatures who suffer. If we gain the power to intervene in a natural world "red in tooth and claw," yet decline to use it, are we morally responsible for the animal suffering that we could have prevented?

Given the power to alter the workings of the natural world, are we morally obligated to use it?

The scenario that may redefine our relationship with the natural world begins with fine clothing. You're dressed to the nines for a formal event, but you arrived early, and it's such a beautiful day that you decided to take a stroll by the nearby lake. Suddenly, you hear the sound of splashing and screams. A child is drowning! Will you dive in to save them? Or let them die, and preserve your expensive outfit?

The philosopher Peter Singer posited this scenario to show that we are all terrible human beings. Just about everyone would save the child and ruin the outfit... leading Singer to question why so few of us give equivalent amounts of money to save children on the other side of the world. The Against Malaria Foundation averages one life saved for every $7000.

But despite having a local bias, our moral compasses aren't completely broken. You never even considered letting the child drown because the situation wasn't your fault. That's because the cause of the problem simply isn't relevant: as the one who could intervene, the consequences are on your head. We are morally responsible for intervening in situations we did not create.

There is a critical difference between Singer's original scenario and the one above: in his version, it was a muddy pond. Any adult can rescue a child from a muddy pond, but a lake is different; you can only save the child if you know how to swim. We only become morally responsible when we acquire the power to intervene.

Few would disagree with either of these moral statements, but when they are combined with increasingly powerful technologies, the implications are deeply unsettling. Given the power to alter the workings of the natural world, are we morally obligated to use it? Recent developments suggest we had best determine the answer soon because, technologically, we are learning to swim. What choices will we make?

Gene drive is a natural phenomenon that occurs when a genetic element reliably spreads through a population even though it reduces the reproductive fitness of individual organisms. Nature has evolved many different mechanisms that result in gene drive, so many that it's nearly impossible to find an organism that doesn't have at least one driving element somewhere in its genome. More than half of our own DNA comprises the broken remnants of gene drives, plus a few active copies.

Scientists have long dreamed of harnessing gene drive to block mosquito-borne disease, with little success. Then came CRISPR genome editing, which works by cutting target genes and replacing them with a new sequence. What happens if you replace the original sequence with the edited version and an encoded copy of the CRISPR system? Gene drive.

CRISPR is a molecular scalpel that we can use to cut, and therefore replace, just about any DNA sequence in any cell. Encode the instructions for the CRISPR system adjacent to the new sequence, and genome editing will occur in the reproductive cells of subsequent generations of heterozygotes, always converting the original wild-type version to the new edited version. By ensuring that offspring will all be born of one sex, or by arranging for organisms that inherit two copies of the gene drive to be sterile, it's theoretically possible to cause a population crash.

(Credit: Esvelt)

When my colleagues and I first described this technology in 2014, we initially focused on the imperative for early transparency. Gene drive research is more like civic governance than traditional technology development: you can decline a treatment recommended by your doctor, but you can’t opt out when people change the shared environment. Applying the traditional closeted model of science to gene drive actively denies people a voice in decisions intended to affect them - and reforming scientific incentives for gene drive could be the first step to making all of science faster and safer.

But open gene drive research is clearly aligned with virtually all of our values. It's when technology places our deepest moral beliefs in conflict that we struggle, and learn who we truly are.

Two of our strongest moral beliefs include our reverence for the natural world and our abhorrence of suffering. Yet some natural species inherently cause tremendous suffering. Are we morally obligated to alter or even eradicate them?

To anyone who doubts that the natural world can inflict unimaginable suffering, consider the New World screwworm.

Judging by history, the answer depends on who is doing the suffering. We view the eradication of smallpox as one of our greatest triumphs, clearly demonstrating that we value human lives over the existence of disease-causing microorganisms. The same principle holds today for malaria: few would argue against using gene drive to crash populations of malarial mosquitoes to help eradicate the disease. There are more than 3500 species of mosquitoes, only three of which would be affected, and once malaria is gone, the mosquitoes could be allowed to recover. It would be extremely surprising if African nations decided not to eradicate malaria.

The more interesting question concerns our moral obligations to animals in the state of nature.

To anyone who doubts that the natural world can inflict unimaginable suffering, consider the New World screwworm, Cochyliomyia hominivorax. Female screwworm flies lay their eggs in open wounds, generating maggots that devour healthy tissue, gluttonously burrowing into the flesh of their host until they drop, engorged and sated, to metamorphose. Yet before they fall, the maggots in a wound emit a pheromone attracting new females, thereby acting as both conductors and performers in a macabre parade that consumes the host alive. The pain is utterly excruciating, so much so that infested people often require morphine before doctors can even examine the wound. Worst of all, the New World screwworm specializes in devouring complex mammals.

Every second of every day, hundreds of millions of animals suffer the excruciating agony of being eaten alive. It has been so throughout North and South America for millions of years. Until 2001, when humanity eradicated the last screwworm fly north of Panama using the “sterile insect technique”. This was not done to protect wild animals or even people, but for economic reasons: the cost of the program was small relative to the immense damage wrought by the screwworm on North American cattle, sheep, and goats. There were no obvious ecological effects. Despite being almost completely unknown even among animal rights activists, the screwworm elimination campaign may well have been one of the greatest triumphs of animal well-being.

Unfortunately, sterile insect technique isn't powerful enough to eradicate the screwworm from South America, where it is more entrenched and protected by the rougher terrain. But gene drive is.

Contrary to news hype, gene drive alone can't cause extinction, but if combined with conventional measures it might be possible to remove targeted species from the wild. For certain species that cause immense suffering, we may be morally obligated to do just that.

(Credit: Esvelt)

South Americans may well decide to eradicate screwworm for the same economic reasons that it was eradicated from North America: the fly inflicts $4 billion in annual damages on struggling rural communities that can least afford it. It need not go extinct, of course; the existence of the sterile insect facility in Panama proves that we can maintain the screwworm indefinitely in captivity on already dead meat.

Yet if for some reason humanity chooses to leave the screwworm as it is - even for upstanding moral reasons, whatever those may be - the knowledge of our responsibility should haunt us.

Tennyson wrote,

Are God and Nature then at strife,
That Nature lends such evil dreams?
So careful of the type she seems,
So careless of the single life.

Evolution by natural selection cares nothing for the single life, nor suffering, nor euphoria, save for their utility in replication. Theoretically, we do. But how much?

[Editor's Note: This story was originally published in May 2018. We are resurfacing archive hits while our staff is on vacation.]

Kevin Esvelt
Kevin M. Esvelt is an assistant professor of the MIT Media Lab, where he leads the Sculpting Evolution Group in exploring evolutionary and ecological engineering. The first to identify the potential for CRISPR “gene drive” systems capable of unilaterally altering wild populations of organisms, Esvelt and his colleagues defied scientific tradition by revealing their findings and calling for open discussion and safeguards before they demonstrated the technology in the laboratory. At MIT, the Sculpting Evolution Group develops local “daisy drives” for community-based environmental editing, which may be able to save endangered species and restore populations to their original genetics. Esvelt's work has appeared in major scientific journals, including Nature and Science, and features regularly in popular media, including The New York Times, The New Yorker, and NPR.

New research challenges the popular notion that all commercial breeding kennels are inhumane.

(© sommai/Adobe Stock)

Candace Croney joined the faculty at Purdue University in 2011, thinking her job would focus on the welfare of livestock and poultry in Indiana. With bachelor's, master's, and doctoral degrees in animal sciences, her work until then had centered on sheep, cattle, and pigs. She'd even had the esteemed animal behaviorist Temple Grandin help shape her master's research project.

Croney's research has become the first of its kind in the world—and it's challenging our understanding of how dog breeding is being done.

Then came an email from a new colleague asking Croney to discuss animal welfare with some of Indiana's commercial dog breeders, the kind who produce large quantities of puppies for sale in pet stores.

"I didn't even know the term commercial breeders," Croney says. "I'd heard the term 'puppy millers.' That's pretty much what I knew."

She went to the first few kennels and braced herself for an upsetting experience. She's a dog lover who has fostered shelter mutts and owned one, and she'd seen the stories: large-scale breeders being called cruel and evil, lawmakers trying to ban the sale of commercially bred puppies, and constant encouragement to rescue a dog instead of paying into a greedy, heartless "puppy mill" industry.

But when she got to the kennels, she was surprised. While she encountered a number of things she didn't like about the infrastructure at the older facilities—a lack of ventilation, a lot of noise, bad smells—most of the dogs themselves were clean. The majority didn't have physical problems. No open sores. No battered bodies. Nothing like what she'd seen online.

But still, the way the dogs acted gave her pause.

"Things were, in many regards, better than I thought they would be," Croney says. "Google told me the dogs would be physically a mess, and they weren't, but behaviorally, things were jumping out at me."

While she did note that some of the breeders had play yards for their pups, a number of the dogs feared new people and things like leashes because they hadn't been exposed to enough of them. Some of the dogs also seemed to lack adequate toys, activities, and games to keep them mentally and physically stimulated.

But she was there strictly as a representative of the university to ask questions and offer feedback, no more or less. A few times, she says, she felt like the breeders wanted her to endorse what they were doing, "and I immediately got my back up about that. I did not want my name used to validate things that I could tell I didn't agree with. It was uncomfortable from that perspective."

After sharing the animal-welfare information her colleague had requested, Croney figured that was that. She never expected to be in a commercial kennel again. But six months later, her phone rang. Some of the people she'd met were involved in legislative lobbying, and they were trying to write welfare standards for Indiana's commercial breeders to follow.

In the continuing battle over what is, and is not, a "puppy mill," they wanted somebody with a strong research background to set a baseline standard, somebody who would actually bring objectivity to the breeder-activist conflict without being on one side or the other.

In other words, they wanted Croney's help to figure out not only appropriate enclosure sizes, but also requirements for socialization and enrichment activities—stimulation she knew the dogs desperately needed.

"I thought, crap, how am I not going to help?" she recalls. "And they said, 'Well how long will that take? A couple of weeks? A month?'"

Dr. Croney with Theo, whom she calls "a beloved family member of our research team."

(Photo credit: Purdue University/Vincent Walter)

Six years later, Croney's research remains ongoing. It has become the first of its kind in the world—and it's challenging our understanding of how dog breeding is being done, and how it could and should be done for years to come.

How We Got Here

Americans have been breeding pet dogs in large-scale kennels since World War II. The federal standard that regulates those kennels is the Animal Welfare Act, which President Johnson signed into law in 1966. Back then, people thought it was OK to treat dogs a lot differently than they do today. The law has been updated, but it still allows a dog the size of a Beagle to be kept in a cage the size of a dishwasher all day, every day because for some dogs, when the law was written, having a cage that size meant an improvement in living conditions.

Countless commercial breeders, who are regularly inspected under the Animal Welfare Act, have long believed that as long as they followed the law, they were doing things right. And they've seen sales for their puppies go up and up over the years. About 38 percent of U.S. households now own one or more dogs, the highest rate since the American Veterinary Medical Association began measuring the statistic in 1982.

Consumers now demand eight million dogs per year, which has reinforced breeders' beliefs that despite what activists shout at protests, the breeders are actually running businesses the public supports. As one Ohio commercial breeder—long decried by activists as a "puppy mill" owner—told The Washington Post in 2016, "This is a customer-driven industry. If we weren't satisfying the customer, we'd starve to death. I've never seen prices like the ones we're seeing now, in my whole career."

That breeder, though, is also among leading industry voices who say they understand that public perception of what's acceptable and what's not in a breeding kennel has changed. Regardless of what the laws are, they say, kennels must change along with the public's wishes if the commercial breeding industry is going to survive. The question is how, exactly, to move from the past to the future, at a time when demands for change have reached a fever pitch.

"The Animal Welfare Act, that was gospel. It meant you were taking care of dogs," says Bob Vetere, former head of the American Pet Products Association and now chairman of the Pet Leadership Council. "That was, what, 40 years ago? Things have evolved. People understand much more since then—and back then, there were maybe 20 million dogs in the country. Now, there's 90 million. It's that dramatic. People love their dogs, and everybody is going to get one."

Vetere became an early supporter of Croney's research, which, unbelievably, became the first ever to focus on what it actually means to run a good commercial breeding kennel. At the start of her research, Croney found that the scientific literature underpinning many existing laws and opinions was not just lacking, but outright nonexistent.

"We kept finding it over and over," she says of the literature gaps, citing common but uninformed beliefs about appropriate kennel size as just one example. "I can't find any research about how much space they're supposed to have. People said, 'Yeah, we had a meeting and a bunch of people made some recommendations.'"

She started filling in the research gaps with her team at Purdue, building relationships with dog breeders until she had more than 100 kennels letting her methodically figure out what was actually working for the dogs.

"The measurable successes in animal welfare over the past 50 years began from a foundation in science."

Creating Standards from Scratch

Other industry players soon took notice. One was Ed Sayres, who had served as CEO of the ASPCA for nearly a decade before turning his attention to lobbying efforts regarding the "puppy mill" issue. He recognized that what Croney was doing for commercial breeding mirrored the early work researchers started a half-century ago in the effort that led to better shelters all across America today.

"The measurable successes in animal welfare over the past 50 years began from a foundation in science," Sayres says. "Whether it was the transition to more humane euthanasia methods or how to manage dog and cat overpopulation, we found success from rigorous examination of facts and emerging science."

Sayres, Vetere, and others began pushing for the industry to support Croney's work, moving the goalposts beyond Indiana to the entire United States.

"If you don't have commercial breeding, you have people importing dogs from overseas with no restrictions, or farming in their backyards to make money," Vetere says. "You need commercial breeders with standards—and that's what Candace is trying to create, those standards."

Croney ended up with a $900,000 grant from three industry organizations: the World Pet Association, Pet Food Institute, and the Pet Industry Joint Advisory Council. With their support, she created a nationwide program called Canine Care Certified, like a Good Housekeeping Seal of Approval for a kennel. The program focuses on outcome-based standards, meaning she looks at what the dogs tell her about how well they are doing through their health and behavior. For the most part, beyond baseline requirements, the program lets a breeder achieve those goals in whatever ways work for the dogs.

The approach is different from many legislative efforts, with laws stating a cage must be made three feet larger to be considered humane. Instead, Croney walks through kennels with breeders and points out, for instance, which puppies in a litter seem to be shy or fearful, and then teaches the breeders how to give those puppies better socialization. She helps the breeders find ways to introduce dogs to strangers and objects like umbrellas that may not be part of regular kennel life, but will need to become familiar when the breeding dog retires and gets adopted into a home as a pet. She helps breeders understand that dogs need mental as well as physical stimulation, whether it comes from playing with balls and toys or running up and down slides.

The breeders can't learn fast enough, Croney says, and she remains stunned at how they constantly ask for more information—an attitude that made her stop using the term "puppy mill" to describe them at all.

"Now, full disclosure: Given that all of these kennels had volunteered, the odds were that we were seeing a skewed population, and that it skewed positive," she says. "But if you read what was in the media at the time, we shouldn't have been able to find any. We're told that all these kennels are terrible. Clearly, it was possible to get a positive outcome."

To Buy or Not to Buy?

Today, she says, she's shocked at how quickly some of the kennels have improved. Facilities that appalled her at first sight now have dogs greeting people with wagging tails.

"Not only would I get a dog from them, but would I put my dog there in that kennel temporarily? Yeah, I would."

"The most horrifying thing I learned was that some of these people weren't doing what I'd like to see, not because they didn't care or only wanted money, but because nobody had ever told them," she says. "As it turned out, they didn't know any different, and no one would help them."

For Americans who want to know whether it's OK to get a commercially bred puppy, Croney says she thinks about her own dogs. When she started working with the breeders, there were plenty of kennels that, she says, she would not have wanted to patronize. But now she's changing her mind about more and more of them.

"I'm just speaking as somebody who loves dogs and wants to make sure I'm not subsidizing anything inhumane or cruel," she says. "Not only would I get a dog from them, but would I put my dog there in that kennel temporarily? Yeah, I would."

She says the most important thing is for consumers to find out how a pup was raised, and how the pup's parents were raised. As with most industries, commercial breeders run the gamut, from barely legal to above and beyond.

Not everyone agrees with Croney's take on the situation, or with her approach to improving commercial breeding kennels. In its publication "Puppy Mills and the Animal Welfare Act," the Humane Society of the United States writes that while Croney's Canine Care Certified program supports "common areas of agreement" with animal-welfare lobbyists, her work has been funded by the pet industry—suggesting that it's impure—and a voluntary program is not enough to incentivize breeders to improve.

New laws, the Humane Society states, must be enacted to impose change: "Many commercial dog breeding operators will not raise their standards voluntarily, and even if they were to agree to do so it is not clear whether there would be any independent mechanism for enforcement or transparency for the public's sake. ... The logical conclusion is that improved standards must be codified."

Croney says that type of attitude has long created resentment between breeders and animal-welfare activists, as opposed to actual kennel improvements. Both sides have a point; for years, there have been examples of bottom-of-the-barrel kennels that changed their ways or shut down only after regulators smacked them with violations, or after lawmakers raised operating standards in ways that required improvements for the kennels to remain legally in business.

At the same time, though, powerful organizations including the Humane Society—which had revenue of more than $165 million in 2018 alone—have routinely pushed for bans on stores that sell commercially bred puppies, and have decried "puppy mills" in marketing and fund-raising literature, without offering financial grants or educational programs to kennels that are willing to improve.

Croney believes that the reflexive demonization of all commercial breeders is a mistake. Change is more effective, she says, when breeders "want to do better, want to learn, want to grow, and you treat them as advocates and allies in doing something good for animal welfare, as opposed to treating them like they're your enemies."

"If you're watching undercover videos about people treating animals in bad ways, I'm telling you, change is happening."

She adds that anyone who says all commercial breeders are "puppy mills" needs to take a look at the kennels she's seen and the changes her work has brought—and is continuing to bring.

"The ones we work with are working really, really hard to improve and open their doors so that if somebody wants to get a dog from them, they can be assured that those dogs were treated with a level of care and compassion that wasn't there five or 10 years ago, but that is there now and will be better in a year and will be much better in five years," she says. "If you're watching undercover videos about people treating animals in bad ways, I'm telling you, change is happening. It is so much better than people realize, and it continues to get even better yet."

Kim Kavin
Kim Kavin is a lifelong journalist who has been reporting on and writing about the dog industry for nearly a decade. Her 2012 book Little Boy Blue and her 2016 book The Dog Merchants both won national awards. More recently, Kim won the 2019 Donald Robinson Prize for Investigative Journalism for a piece in The Washington Post that documented a multimillion-dollar river of cash flowing from rescue nonprofits, shelters and dog-advocacy groups through dog auctions into the pockets of dog breeders. Kim lives in New Jersey with her two adopted shelter mutts. Learn more about her at

Two of six female Southern white rhinos who were brought to the San Diego Safari Park to serve as surrogate mothers for the embryos that scientists hope to make from gametes from induced pluripotent stem cells.

(Courtesy Jeanne Loring.)

[Editor's Note: This video is the first of a five-part series titled "The Future Is Now: The Revolutionary Power of Stem Cell Research." Produced in partnership with the Regenerative Medicine Foundation, and filmed at the annual 2019 World Stem Cell Summit, this series illustrates how stem cell research will profoundly impact life on earth. A new video will be published every Monday this month.]

Kira Peikoff
Kira Peikoff is the editor-in-chief of As a journalist, her work has appeared in The New York Times, Newsweek, Nautilus, Popular Mechanics, The New York Academy of Sciences, and other outlets. She is also the author of four suspense novels that explore controversial issues arising from scientific innovation: Living Proof, No Time to Die, Die Again Tomorrow, and Mother Knows Best. Peikoff holds a B.A. in Journalism from New York University and an M.S. in Bioethics from Columbia University. She lives in New Jersey with her husband and son.