Dan Burton has trapped hundreds of wild pigs for clients of his wildlife control company in Salinas, but even he was startled when he cut one of them open and found blue meat inside.

The startling find of wild pigs with bright blue tissue in Monterey County suggests the wild animals have been exposed to the anticoagulant rodenticide diphacinone, a popular poison used by farmers and agriculture companies to control the population of rats, mice, squirrels and other small animals, according to a statement from the California Department of Fish and Wildlife.

“Hunters should be aware that the meat of game animals, such as wild pig, deer, bear and geese, might be contaminated if that game animal has been exposed to rodenticides,”