DENVER – A year after an Idaho boy was sickened and his dog killed by a cyanide “bomb,” federal officials are investigating whether to ban the explosive poison devices used to kill thousands of coyotes and foxes annually.

The cyanide devices known as M-44s look like small sprinkler heads and are designed to spray a fatal dose of poison into the mouth of predators when they bite rotting meat placed atop them. Environmentalists have long opposed their use, arguing they indiscriminately kill and pose a danger to…