The dogs swept all the schools’ lockers. They reacted 14 times at Edison and 13 times at Marshall, said district spokeswoman Sheryl Miller.

When a dog reacts, lockers are searched. Often, nothing is found, although the dogs could have been reacting to residual traces of drugs, police have said.

Students were placed on “soft lockdowns” during the searches, which lasted slightly longer than 30 minutes each. The lockdown keeps students and staff in their classrooms, but classes go on as usual.

These were the sixth and seventh drug-dog searches in Janesville middle and high schools this school year.

All five high and middle schools were searched last fall. If the district follows the pattern, Franklin Middle School and the two high schools are likely to be visited by the dog teams sometime this spring.