Drug-sniffing dogs will become frequent visitors at high schools in St. Louis County’s Parkway School District starting in January.

County police will send a trained dog and handler twice a semester to sniff student lockers, hallways and student cars at all five high schools.

The searches will occur during or after school at no cost to the district.

Slightly more than a dozen other high schools or districts in St. Louis County have similar programs. Officials at Parkway say it’s a preventive measure aimed at ensuring schools and campuses are drug-free.