As South Korea prepares to enforce a nationwide ban on the breeding, slaughter and sale of dogs for meat next year, a troubling question has emerged: What happened to the hundreds of thousands of dogs that once supplied the country's dog meat industry?

Electric prods rest against the wall near rusty cages containing dog skulls in an abandoned canine slaughterhouse in a South Korean town.

As South Korea prepares to enforce a nationwide ban on the breeding, slaughter and sale of dogs for meat next year, a troubling question has emerged: What happened to the hundreds…