Fourteen-year-old Canyon Mansfield was out walking the family Labrador, Casey, on public land in the outskirts of Pocatello, Idaho, last month. As they roamed a hill near their home, Canyon spied a piece of metal protruding from the snowy ground that resembled the head of a garden sprinkler. When he bent down to touch it, the device exploded, jolting him off his feet and emitting a powdery substance. Some of the granules got into his eyes, which he scrubbed out with wet snow.

The bulk of the substance blew downwind into Casey’s face. Within a minute the dog was writhing with convulsions, a reddish foam emanating from his mouth. In front of Canyon, the yellow Lab made guttural sounds then went still.

Heeding the cries for help, Canyon’s parents, Theresa and Mark Mansfield, rushed to the scene. Theresa cradled the dog while Mark, a family physician, administered chest compressions. He was about to try mouth-to-mouth resuscitation when Canyon shouted, “Don’t do it, Dad, I think Casey’s been poisoned.”

All three of them had some of the residue on their skin and clothes. Only by luck did it not get into their mucous membranes, and only later did they learn that this wasn’t just any poison. It was sodium cyanide—a federal Category One toxicant and one of the deadliest substances on Earth.

“When it went off, I was so confused because it caught me by surprise and happened so fast,” Canyon said. “I panicked because the next thing I knew Casey was dying.” Since the incident Canyon has been suffering from headaches, a telltale symptom of exposure to cyanide.

View Images This is the M-44 that emitted the ultra-toxic sodium cyanide that killed the Mansfield's dog. Between 2000 and 2012, activation of these devices resulted in the deaths of 1,200 dogs. Photograph by Bannock County Sheriff's Office, AP

Sodium cyanide is considered by the Department of Homeland Security to be a potential weapon for terrorists. It’s a key ingredient in the M-44s, or “cyanide bombs,” used by Wildlife Services, an obscure agency of the U.S. Department of Agriculture, to kill wildlife predators on public and private lands in the West.

According to the U.S. Environmental Protection Agency, an average of 30,000 M-44s, deployed by the federal government in concert with Western states and counties, are triggered each year. Baited to entice animals, they’re indiscriminate in their victims. So far, no humans have been killed by M-44s. But according to an investigation by the Sacramento Bee, 18 Wildlife Services employees and several other people were exposed to cyanide by M-44s between 1987 and 2012, and between 2000 and 2012 the devices killed more than 1,100 dogs.

Established 120 years ago under a different name, Wildlife Services exists primarily for the benefit of the livestock industry. The agency spends more than $120 million a year killing animals deemed “nuisances” to humans: everything from coyotes and wolves to mountain lions, bears, foxes, bobcats, prairie dogs, and birds (in part to prevent collisions with planes at airports). During the past decade the agency has killed some 35 million animals. It killed 2.7 million in 2016 alone.

In recent disclosure forms Wildlife Services reported that out of 76,963 coyotes killed in 2016 for livestock protection, 12,511 were felled with M-44s. Another 30,000 were gunned down by sharpshooters from fixed-wing planes and helicopters, and 15,000 more died in choking neck snares.

“Predators are a problem [for ranchers], and some of the predators are a problem for game animals,” says John Peavey, a longtime rancher near Carey, Idaho, who has battled coyotes and wolves getting into his cattle herds and sheep flocks. “These devices [M-44s], ugly as they are, are important. They should be highly supervised. They should not be set close to places where people recreate. But they are a tool, especially if properly used.”

While Peavey has sympathy for the Mansfields, he says the press has a fascination with writing only about the predator controversies and poisons when the real issue is maintaining the condition of Western rangelands. He believes some anti-livestock activists are using the poison issue to renew calls for prohibiting cattle and sheep from grazing on public lands.

For decades, however, environmentalists, animal welfare advocates, and some politicians have pushed for Wildlife Services to be radically reformed—if not abolished—arguing that it’s an anachronism.

“Wildlife Services, with much of what it does, adheres to a mind-set better suited to rogue cowboy culture of the 19th century, and it’s just not consistent anymore with modern values,” U.S. Representative Peter DeFazio, a Democrat from Oregon, told National Geographic by phone last week. Over the years DeFazio has pressed for investigations into Wildlife Services related to alleged animal cruelty, budget irregularities, illegal use of toxic chemicals, and convoluted statistics as to how many animals it actually destroys. “It’s an agency that lacks transparency and accountability, and I believe it’s out of control,” De Fazio said.

In a documentary titled, EXPOSED: USDA’s Secret War on Wildlife, former agency trappers corroborate that assertion.

DeFazio said the agency has managed to dodge significant oversight in Congress because of resistance from lawmakers, primarily in the West, who say that lethal removal of predators is essential to protecting the livelihoods of ranchers grazing cattle and sheep on public and private lands.

INCIDENT UNDER REVIEW

Following Casey’s death, Wildlife Services has been mostly silent.

In response to repeated phone calls from National Geographic to offices at local, regional, and national levels, its Washington, D.C., communications office issued the same written statement it circulated on March 17 and has made no further comment since. The statement noted that the incident was under review, that procedures are designed to minimize unintentional run-ins with pets, that precautions were taken and signs put up as warnings, and that such accidents are rare, this being the first in Idaho involving M-44s since 2014.

Dan Argyle, a captain in the Bannock County Sheriff’s Office, told National Geographic that no warning signs were observed at the scene and that a second M-44 had been positioned nearby, then removed by the trapper who put it there.

“As a program made up of individual employees, many of whom are pet owners, Wildlife Services understands the close bonds between people and their pets and sincerely regrets such losses,” the Wildlife Services statement says. “We are grateful that the individual who was with his dog when it activated the M-44 device was unharmed, however, we take this possible exposure to sodium cyanide seriously and are conducting a thorough review of this incident.”

View Images Casey's accidental death has reinvigorated the push for the U.S. government to ban the use of M-44s to kill predators. Photograph courtesy Theresa Mansfield

The statement concluded: “Wildlife Services provides expert federal leadership to responsibly manage one of our nation's most precious resources—our wildlife. We seek to resolve conflict between people and wildlife in the safest and most humane ways possible, with the least negative consequences to wildlife overall. Our staff is composed of highly skilled wildlife professionals who are passionate about their work to preserve the health and safety of people and wildlife.”

On its website, Wildlife Services describes the way M-44s work: “The M-44 device is triggered when a canid (i.e. coyote or wild dog) tugs on the baited capsule holder, releasing the plunger and ejecting sodium cyanide powder into the animal’s mouth. The sodium cyanide quickly reacts with moisture in the animal’s mouth, releasing hydrogen cyanide gas. Unconsciousness, followed by death, is very quick, normally within 1 to 5 minutes after the device is triggered. Animals killed by sodium cyanide appear to show no overt signs of distress or pain.”

The Mansfields, incredulous at that description, say their dog suffered an agonizing death.

Sander Orent, a toxicologist in Boulder, Colorado, has for decades been tracking the USDA’s sanctioning of biocides—including a variation of M-44s called “coyote getters,” which also use cyanide, and lethal collars around the necks of sheep filled with deadly sodium fluoroacetate—to control predator populations. Of death by M-44 he said, “You could compare it to the recent sarin gas attack in Syria because the concept of how cyanide kills is similar. It basically suffocates any living being it comes in contact with. It ties up the ability of the blood to carry oxygen. When that dog is gasping for air, it experiences an extremely uncomfortable feeling of panic and desperation, then it convulses and dies. For an animal experiencing it and a person watching it happen, it would be horrifying.”

Orent, who has served as a scientific adviser to conservationists, said that animals as large as horses and cows have died from coming in contact with M-44s. “They’re frickin’ dangerous, especially when baited. It makes me think of war-torn parts of the world where munitions are meant to look attractive to children so they pick them up.”

According to Orent, who said it was incredibly lucky that neither Canyon nor his parents died or were seriously injured, “There’s no compelling scientific justification for these devices. I think it’s awful a society like ours still allows them to be used, because they’re not necessary.”

PREDATOR AND LIVESTOCK DEATHS

The Department of Agriculture’s Animal and Plant Health Inspection Service publishes an annual report on causes of death for livestock. In most parts of the West, predators rank behind disease, bad weather, and accidents when it comes to livestock deaths.

Predators kill more sheep than cattle, and Idaho ranks in the upper tier of sheep-producing states. In Idaho in 2014 (the most recent year for which numbers are available) predators were blamed for the loss of about 4,600 of the 16,000 lambs and adult sheep that died. (Conservationists dispute the figures.) Most of the losses were lambs taken by coyotes. Predators killed less than one percent of adult sheep. Bad weather, unknown non-predator causes, and lambing problems accounted for most deaths.

The state and federal government pay compensation for livestock killed by wolves, and in some cases Idaho reimburses ranchers for animals taken by mountain lions and black bears. Damages are not paid for kills by coyotes. Payments can range from a couple of hundred dollars for a lamb to a few thousand dollars for a cow.

Consistent statistics are often out of date, and it’s hard to reconcile different numbers presented by various agencies. Ranchers often say predators take more livestock than are officially reported, but some former Wildlife Services trappers, such as Carter Niemeyer, who wrote a memoir titled Wolfer about his career as an animal control specialist, say predator kills are often exaggerated and that statistics put into reports can’t always be trusted.

Niemeyer was a government trapper for several decades before retiring a few years ago. As a senior Wildlife Services director in Montana, he said that he and the agency trappers who reported to him had serious misgivings about using M-44s. “Trappers didn’t like using them because they’re dangerous and kill indiscriminately,” he said. Even when Niemeyer argued that there were better options for controlling coyotes, the agency’s "clients"—ranchers—would demand that M-44s be deployed against his objections, he said, noting that M-44s can indeed kill other non-target species, including wolves, bears, imperiled wolverines, and Canada lynxes.

“I’ve had half a dozen government trappers tell me that ranchers routinely inflate the number of losses that occur,” said Brooks Fahy, founder of Predator Defense, a conservation organization in Eugene, Oregon, devoted to advancing public understanding of predators. In some cases, he said, they “aren’t suffering losses at all, yet they just want Wildlife Services to come in and prophylactically kill predators whether they’re a problem or not.”

Whatever the actual numbers, one recent study showed that the best science done on predator control reveals that non-lethal methods are more effective than lethal ones at reducing livestock losses. But because strategies such as guard dogs, range riders, flashing lights, fencing, lamb sheds, and trapping and relocating predators can be more expensive, they’re less favored.

“The whole premise for Wildlife Services’s existence is based on a crumbling foundation of misinformation,” asserts Wendy Keefover, carnivore protection manager for the Humane Society of the United States, based in Colorado. “Cattle losses from wild carnivores and feral dogs together amount to 0.23 percent of the entire U.S. cattle inventory. For that reason alone it makes no sense for the federal agents to use chemical warfare on animals.”

On April 4 the Humane Society—along with the Center for Biological Diversity, Wildlife Guardians, and the Fund for Animals—sued the U.S. Fish and Wildlife Service, which, under the domain of the U.S. Department of the Interior Department, has management jurisdiction over endangered species. The lawsuit alleges that the service has failed to consider the impacts of Wildlife Services poisons on protected animals such wolves, grizzly bears, swift foxes, lynxes, raptors, black-footed ferrets, and others. Black-footed ferrets, the most endangered land mammal in North America, depend on a diet of prairie dogs, which have been poisoned in the millions by Wildlife Services. As of April 20, the Fish and Wildlife Service had not responded to the suit.

A FORMER INSIDER’S EXPERIENCE

Sam Sanders, who has a degree in biology from the University of Nevada-Reno, spent seven years, from 2004 to 2011, with Wildlife Services as a trapper and manager in northern Nevada. He called attention, he claims, to alleged violations of the law and protocols, but his complaints fell on deaf ears.

Today Sanders, who resigned from Wildlife Services because he felt the agency wasn’t seriously addressing problems, is an animal control specialist in the private sector. He told National Geographic that he’s regulated more stringently now than he was at Wildlife Services. He still has a few friends at the agency and said that “WS and I compete for a variety of work, including urban work at airports, rural work protecting livestock, and wildlife protection as well. So I’m fairly well informed.”

Contrary to Wildlife Services’ claims of being an industry leader in ethical animal control, Sanders said that not all its agents monitor their equipment (M-44s, leg-hold traps, and snares) in a timely way or post adequate warning signs. With regard to leg-hold traps, Sanders says animals caught in them can linger in pain for a week before they’re put out of their misery.

View Images A Wildlife Services trapper in Idaho holds a wolf shot from the air. Photograph courtesy USDA

“The management doesn’t want to fix the problems,” Sanders said. “They keep hiding behind the Freedom of Information Act and forcing the public to use the law to get information. They tell employees to don’t ever put anything in writing, and they promote the notion of ‘plausible deniability,’ so that if anyone brings up things that go wrong, you just deny it happened.”

Sanders doesn’t use M-44s anymore. But, he said, “If you want to control predators, M-44s are effective tools, and there are responsible trappers out there who use them. I know, because I was one of them. But M-44s can be misused, and they have been to the point where stupid things can happen, involving irresponsible management, like the incident in Pocatello.”

And, he added, M-44s are “better from an animal welfare perspective than some of the ready-available alternatives.” People can buy rat poison from hardware stores and pepper it into animal carcasses left as bait for coyotes that can also kill pets and non-target animals. Sanders said he knows of people pouring gasoline into the dens of predators or starting fires that suck all the oxygen out of animal dens, causing death by suffocation. Not long ago he learned of a trapper who claimed to use large treble fishing hooks baited with meat dangling four feet off the ground. Predators reaching for the meat would suffer a gruesome death by choking and hanging.

For those who seek a ban on the use of M-44s, Sanders cautions that “you have to think of unintended consequences. People are going to employ other alternatives and come up with their own,” he said. “Until there’s a better way that solves conflicts between predators and livestock in ranch country, predators are gonna get it one way or another. Just because you ban what you believe is the bad stuff doesn’t mean it will stop the killing.”

IS POCATELLO A TIPPING POINT?

According to Brooks Fahy, public outrage sparked by the death of the Mansfields' dog represents a tipping point in bringing the kind of scrutiny to bear on Wildlife Services that opponents say has been lacking.

“Wildlife Services has taken a beating for its controversial aerial gunning and gassing of predators, its trapping and snaring, but its use of deadly poisons has been a dirty little secret, especially where it has placed unsuspecting people and their pets in danger,” Fahy said. “This time it can’t run away from the truth.”

The trapper working for the Idaho branch of Wildlife Services mistakenly placed the M-44 that killed Casey on Bureau of Land Management land near the Mansfields' residential subdivision, despite the agency’s promise last November, following a review of options for dealing with predators, not to use M-44s on public land in Idaho.

“It’s a fact that it was installed on BLM land,” Bannock County Sheriff Lorin Nielsen told a reporter in Idaho. “It was about 300 yards from the residence, and there were no posted warning signs at the time this happened. All three of those are violations of the protocol.”

On March 28 Western Watersheds, an advocacy group that monitors effects of livestock grazing on public lands, and 19 other conservation organizations submitted a petition calling on Wildlife Services to end the use of M-44 cyanide bombs in Idaho and retrieve all those now in place in the state.

Wildlife Services complied, ordering three dozen existing M-44s to be removed and temporarily banning use of M-44s in Idaho.

Congressman DeFazio said that doesn’t go far enough and that the ban needs to be applied nationwide. But, he added, at least “Idaho and Wildlife Services are now under a spotlight.” On March 30 DeFazio submitted a House bill, “The Chemical Poison Reduction Act of 2017,” calling for a total ban on M-44s in the name of public health, animal welfare, and national security.

Meanwhile the Bannock County prosecutor’s office is deciding what criminal or misdemeanor charges to bring against Wildlife Services.

Theresa Mansfield told National Geographic that no one from the agency reached out to to express sympathy for the family’s ordeal. She and Canyon went down to the Wildlife Services office in Pocatello and happened to meet the trapper who deployed the M-44.

“When I confronted him face to face, he said, ‘I’m sorry this happened to your son and dog,’ but, really, what else could he do standing in front of an upset mother and her child who could’ve been killed?” Theresa said. “It angers me that no one from Wildlife Services had the decency to reach out. All Wildlife Services did was issue a cut-and-paste statement to the public. I’ve been told they’re unwilling to apologize personally to us because that would be an admission of guilt.”

Fahy said this is consistent with Wildlife Services’ previous responses to other families who lost pets to M-44s or had members get sick by coming in contact with them. “It fits a troubling pattern. In the past Wildlife Services has actually implied that people may seek out M-44s and get their dogs killed so they might sue and collect a huge settlement from the government,” he said. “So their posture is to deny.”

On June 21, 2006, Michael J. Bodenchuk, then the state director of Wildlife Services in Utah, wrote a memo stating why he didn’t want to pay damages to a woman who lost a dog to M-44 poisoning. "I have concerns about the government settling cases with dog owners because it is all too easy for someone to intentionally take a dog into an area posted with signs with the intention of getting the dog killed,” Bodenchuk said.

Theresa and her husband are considering filing a lawsuit against Wildlife Services. They’ve written to President Donald Trump asking him to take action, and they plan to travel to Washington, D.C., in support of DeFazio’s legislation.

Never in their worst dreams, Theresa said, would they have imagined their son becoming a poster child for the need to reform a government agency. For now the couple is focusing on being profoundly grateful that their teenage son is still alive.

“Any time Canyon talks about it, his mood instantly changes,” Theresa said. “He feels responsible for what happened to Casey. He asks, ‘What if I hadn’t touched it? What if I hadn’t gone outside. He questions why he went up that hill, and I tell him that none of this is your fault. Canyon will carry the memory of what happened to his favorite dog for the rest of his life.”

Environmental journalist Todd Wilkinson has been writing about the West for more than 30 years. He is the author of several books, including the recent award-winning Grizzlies of Pilgrim Creek, An Intimate Portrait of 399, the Most Famous Bear in Greater Yellowstone. He contributed to National Geographic’s May 2016 special issue on Yellowstone National Park. Follow him on Twitter.