John Peckham, believes his Bramhall High School, in Stockport, Greater Manchester, is the first in the country to mount random drug searches. Parents and governors welcomed the scheme, although civil rights campaigners opposed it.
Mr Peckham said: "Just as the fear of being breath-tested deters many adults from drinking and driving, so the very remote possibility of being caught in school with an illegal drug will also act as a deterrent for many young people.
"We see this as part of a comprehensive programme to reduce the harm that drugs do - and the best way to avoid harm is not to become involved. Most of our students choose that route."
Mr Peckham said that he employed the labrador named Scuba and handler Steve Warren to protect the majority of the 1,450 comprehensive pupils who had never touched drugs. He hoped the sniffer dog's presence would deter the small number of pupils who dealt in cannabis on school grounds.
Mr Warren, who runs Sovereign Specialised Security in Macclesfield, checked the changing rooms, cloakrooms and public areas such as the school's perimeter fence.
The search, which cost pounds 35, was part of a broader campaign against drugs at the school which included teachers smelling a massage oil made with cannabis to acquaint themselves with the smell.
Max Hunt, Stockport chief education officer, said using a sniffer dog might worry younger pupils.
A spokesman for the Greater Manchester branch of Liberty, the campaigning organisation for civil rights, said: "All the agencies agree that cannabis use and alcohol use should be treated with counselling and sympathetically.
"If pupils feel they are not getting this support because of the way the searches are done, that is sending out the wrong kind of messages."
But Mr Peckham has faith in his initiative and has warned pupils that Scuba could be back at any time.
The suspended boys were suspected of possessing cannabis, the headmaster said.Reuse content