One dog was led past about 900 lockers while students were locked in their classrooms, said Sheryl Miller, district spokeswoman. The search took about 32 minutes, she said.
No physical education lockers were searched, Miller said.
The dog did react at 15 lockers at Marshall, but no evidence of drugs was found.
This completes a sweep of all the school districts' secondary schools this fall. Miller has said that officials hoped to do dog searches at all five schools once a semester this year.
No drugs were found in any of the searches, although dogs reacted to lockers at all the schools.