SALT LAKE CITY — A cyanide bomb that killed a family's pet Labrador and sent a teenager to the hospital earlier this month in Pocatello is a predator control device commonly used by the federal government to kill coyote in Utah and 15 other states around the country, mostly in the West.

The bombs, called M-44s, come with a package of 26 strict rules and regulations from the U.S. Environmental Protection Agency regarding their use, including the requirement they be clearly marked and not placed in locations where contact with the public or pets is probable.

Despite the litany of requirements — including being checked weekly and accompanied by a 25-foot elevated sign of warning — those federal rules apparently were not followed on the day 14-year-old Canyon Mansfield came across a bomb just 350 yards from his property line.

Canyon took his 3-year-old Labrador, Casey, to the public land behind his home on March 16 to pray and reflect.

"He spends a lot of time up there," said Canyon's mother, Theresa Mansfield. "He likes to read his adventure Bible."

Canyon saw what looked like a sprinkler head jutting from the ground. He bent over, touched it and the spring-loaded device exploded, ejecting cyanide powder that transforms to gas when it hits the air.

Canyon was momentarily blinded and immediately doused his face and eyes in snow, his mother said. Nearby, his dog was whining and grumbling. Casey was dead within just a few minutes.

"It basically suffocates you from the inside out," Mansfield said. "He watched Casey take his last breath. My child will have to live with that image the rest of his life."

Fear and panic

Members of the Bannock County Sheriff's Office and the local fire department responded to the Mansfield home. Soon after, the bomb squad arrived.

"We were all in disbelief," she said.

An ambulance crew rushed Canyon to the hospital, where he was treated and later released. Once emergency personnel realized what the family and they were exposed to, Mansfield said everyone had to enter the hospital via a special entrance to avoid further contamination.

The sheriff's office, property owners and hospital staff had no idea that the device — and at least one other — had been placed on the land by Wildlife Services, a federal branch of the government within the U.S. Department of Agriculture, said Bannock County Sheriff's Capt. Dan Argyle.

"We were told there were a few other devices up there and they were removed pronto after this incident," he said. "Given what has happened, I think we as a sheriff's office don't want to see any of those devices out there, and we don't want them used again. I know our sheriff feels very strong about that."

Argyle said a Wildlife Services employee who responded that day said there is supposed to be community notification when the agency sets out M-44s and their locations should be clearly marked.

"We never saw anything that the community up there was notified and anyone who lives up there says they never seen anything that was posted," Argyle said. "They said they notified people and that it was marked; we never found anything to say that was the case."

The device was found on Bureau of Land Management land, according to the coordinates obtained by the sheriff's office.

Mansfield said the employee who planted the devices told her he put them out in late February.

Critics of M-44s said their placement behind the Mansfields' property contradicts a 2016 decision by multiple agencies to stop the use of cyanide bombs on public lands in Idaho. The decision document clearly states that Wildlife Services would discontinue the use of M-44s on Idaho public lands in response to public comments it had received for its predator control plan in the state.

"It never should have been there at all," said Erik Molvar, executive director of the Western Watersheds Project, a conservation group critical of the devices.

"M-44s and other traps and toxic chemicals that Wildlife Services uses to kill predators are a public safety hazard," added Talasi Brooks, of Advocates for the West, a nonprofit environmental law firm.

"If Wildlife Services is putting these devices in places were people recreate or walk their dogs, the public deserves to know about it."

Wildlife Services issued a statement in the aftermath of the Pocatello incident but will not discuss details of the case or affirm whether a 2010 agencywide directive on M-44 use is still in effect.

“(Wildlife Services) confirms the unintentional lethal take of a dog in Idaho. 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," said spokesman Andre Bell.

"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."

Mansfield said the statement offends her.

"They did not 'take' my dog — they murdered him," she said. "Because if they took my dog, they could bring him back."

M-44s in Utah

Wildlife Services has been operating in Utah since at least the 1930s or 1940s, according to Greg Sheehan, executive director of the Utah Division of Wildlife Services.

The federal agency has a cooperative partnership with the state wildlife services and the Utah Department of Agriculture and Food. State wildlife helps to pay for the federal activities at an annual cost of about $650,000, while the state agriculture department chips in about $1.2 million in funding and employee support.

Last year, M-44s killed 56 coyotes in Utah and two foxes. In 2015, the cyanide bombs killed 68 coyotes and six red foxes, according to an agency database.

The federal agency operates in Utah with the consent of a nine-member board led by LuAnn Adams, Utah's commissioner of agriculture and food.

Adams said M-44s have not been deployed on federal lands in Utah for five years and are only put on private property at the request of the property owner, such as a rancher or sheepherder who is experiencing predation losses from coyotes.

"I have talked with the federal folks, and they have assured me they do not put these on public lands and they won't be doing it," she said. In 2006, a Utah woman's 2-year-old German shepherd died after coming across an M-44 in Millard County during a rockhounding trip.

Adams said she is not aware of any recent incidents.

The Utah director of the federal program, Chad Heuser, said he was not authorized to speak to the media about its activities in Utah, but both Sheehan and Adams said Wildlife Services' employees perform a critical function.

Sheehan said if there is a problem bear in a campground or marauding cougar, these are the experts they call.

Wildlife Services also scatters flocks of birds at the Salt Lake City International Airport to minimize risk of bird strikes with aircraft.

"We have a strong working relationship with Wildlife Services and they effectively do the types of control for the species we ask them to manage," Sheehan said. "We have never asked to have any of those sorts of toxic materials used for the benefit of wildlife, to my knowledge."

M-44s are a spring-activated device smeared with scented bait to attract coyotes and make them bite and pull on them. They deliver a dose of cyanide powder in a capsule that is registered as a restricted-use pesticide by the EPA, which has more than two dozen rules governing their use.

In addition, states may have additional restrictions on M-44s.

Sodium cyanide is a highly toxic chemical asphyxiant, according to the U.S. Centers for Disease Control and Prevention. Because it interferes with the body's ability to use oxygen, it is rapidly fatal. Sodium cyanide can affect the body through ingestion, inhalation, skin contact or eye contact.

Mansfield said the federal agency still has possession of her dog's body and her son's clothes.

Although she has visited their offices, she said she can't get any answers.

"They're getting a ton of pressure on them. This neighborhood is full of dogs and kids and people who love to hike," she said.

Wildlife Services would not disclose specifics of M-44 use in Utah, but an environmental analysis on the agency's activities in the state shows that about 77 M-44s were used in fiscal year 2015.

The agency is supposed to have signed formal agreements in place with property owners before any M-44 deployment, but it would not disclose how many exist in Utah. Its spokesman referred questions about M-44s to the agency's fact sheet on the devices.

Dogs and cyanide bombs

According to its own 2016 database, the agency said systemwide it unintentionally "took" 29 dogs through traps or other means and intentionally took 181 more.

Bethany Cotton, wildlife program director with WildEarth Guardians, said it is impossible to tell how many of those dogs may have been someone's pet because of the agency's classification system that only says they were free-roaming, feral or hybrid.

"It's difficult," she said. "Were these animals that were just off-leash?"

WildEarth Guardians, an environmental organization, has waged a long campaign against Wildlife Services to push it to adopt nonlethal means of predator control.

"The (Pocatello incident) shows how dangerous the M-44s are. They are extremely dangerous, and people have no idea where they are. For well over a decade, the guardians have worked to rein in the cruel tools that Wildlife Services uses."

Just a few days earlier in Wyoming, two families with their dogs happened upon a pair of M-44s. Brooks Fahy, with Predator Defense, said they were hunting for shed antlers. Both dogs died.

"It turned into a complete horror show," Fahy said. Wildlife Services later released a statement that said it does not provide predator damage control in that area.

Fahy has been working on banning M-44s for 40 years and said the devices are barbaric and unnecessary.

Predation losses to sheep and cattle herds in Utah and the West are significant, however, and Adams said the work Wildlife Services does is crucial.

In 2015, coyotes accounted for 65 percent of confirmed kills of livestock, according the agency's environmental analysis. The Utah Department of Agriculture and Food estimated sheep and lamb losses in 2014 at a value of $4.5 million, which experts figure is only a fraction of the loss because not all kills are reported.

"It has been a really good program," Adams said. "When you see the damage that can be done to small animals by these predators, it makes you sick."

But Mansfield, who comes from a ranching and farming family in Kentucky, said she'd never heard of M-44s.

"I don't understand the need for these horrible bombs," she said. "I feel like I have had terrorism in my backyard."

She said her son, Canyon, had actually gone onto the public land that day to pray because of some spiritual struggles. What she said should have been a quiet moment of reflection turned into a deadly nightmare.

"The entire day he kept thinking he was being punished by God because he was already questioning Lent and if he could be better," she said. "It could just as easily been him."

Like Mansfield, the Bannock County Sheriff's Office is dismayed a cyanide bomb was planted in their midst.

"It is pretty much a miracle in this case that the boy was not injured or killed. He was standing directly over the device," Argyle said. "The wind was blowing so hard, it must have taken it (the cyanide) directly away from him and into the dog. He is very lucky."