DES MOINES, Iowa (AP) — After spending two decades raising pigs to send to slaughterhouses, Dean Meyer now faces the mentally draining, physically difficult task of killing them even before they leave his northwest Iowa farm.

Meyer said he and other farmers across the Midwest have been devastated by the prospect of euthanizing hundreds of thousands of hogs after the temporary closure of giant pork production plants due to the coronavirus.

The unprecedented dilemma for the U.S. pork industry has forced farmers to figure out how to kill healthy hogs and dispose of carcasses weighing up to 300 po...