Investigators are trying to determine exactly what caused the mysterious deaths of about 200 cows in Portage County, Wisconsin.
The dead cattle were found on a farm in Amherst, which is about 50 miles southeast of Wausau.
Law enforcement officials say the animals likely died of a virus that causes respiratory and reproductive problems.
They say the farm owner has been working with a veterinarian and samples from the dead animals have been sent to Madison for testing.
Investigators say there's no threat to people or other animals.