By Laura Zuckerman

(Reuters) - Conservation and animal welfare groups sued the U.S. government this week over its use of so-called cyanide bombs to kill coyotes after the devices were blamed for the deaths of a protected wolf and three pet dogs.

The Center for Biological Diversity, the Humane Society and others said in the lawsuit that the U.S. Fish and Wildlife Service, which is tasked with protecting endangered animals, failed to assess the threat posed to species when another agency started using cyanide bombs and a poison called Compound 1080.

Cyanide bombs, or M-44s, shoot a gram of cyanide sodium into the mouths of animals lured by baits. A liquid form of Compound 1080 can be contained in collars placed on livestock like sheep and goats.

The spring-loaded mechanism accidentally killed an endangered wolf in Oregon in February and in March caused the death of three pet dogs, one in Idaho and two in Wyoming, according to the lawsuit.

Wildlife Services, which deploys the devices, is an arm of the U.S. Department of Agriculture that targets animals considered nuisances to farms and ranches.

Last year, cyanide bombs placed by the agency killed 13,530 animals, most of which were coyotes and foxes, according to the lawsuit. More than 320 of the animals killed by M-44s in 2016 were not targeted for death and included everything from raccoons to pet dogs, the lawsuit said.

Wildlife Services, which is not named as a defendant in the lawsuit, did not respond to requests for comment.

The U.S. Fish and Wildlife Service did not immediately respond to an interview request. The lawsuit was filed in U.S. District Court in Missoula, Montana.

"I'm outraged that the feds place cyanide bombs where they can kill endangered wildlife," Collette Adkins of the Center for Biological Diversity said in an email.

In the lawsuit, the groups asked that a judge force federal wildlife managers to analyze the effects of M-44s and Compound 1080 on wolves, grizzly bears and Canada lynx and to ban the use of the poisons in the habitats of so-called imperiled species that are in decline.

After a cyanide bomb temporarily blinded a 14-year-old boy in Pocatello, Idaho and killed his dog on March 16, Wildlife Services said in a statement that it tried to minimize hazards to pets and humans by posting warnings and that M-44s were only set at the request of property owners or managers.

More From Missoula Current