Reiner Reuther of sniffer dog enterprise www.drogenhunde.de believes techniques teenagers use to secrete their drug use can often be "too sophisticated" for parents to uncover. But nothing gets past his dog Thor, he says.
Thor completed his training to become a police dog in Texas and is known for his alacrity in sniffing out cannabis, heroin, speed and ecstasy.
"In America it is common practice for sniffer dogs to come by to school buildings and yards every two to three weeks. In most of the schools drug finds went down by up to 90 percent," he told news portal www.express.de.
"Parents get in touch with me and arrange an appointment," he said. "When the children are at school I come around with Thor. If drugs are found, it is up to our clients whether or not they choose report it."
A flyer printed on the firm's website offers searches of "children's bedrooms, apartments [and] cars" and describes Thor as "at update on the latest drugs on the market."
It also stresses that uniforms must not - but can be - worn according to clients' wishes and that staff drive either "nondescript or marked vehicles (for deterrence)".
If Thor comes up trumps, says Reuther, it is up to his clients to decide what to do. He cites one case where worried parents had called the police for sniffer-dog search, and the officers who found the teenage son was smoking hash were obliged to report it.
Rather than the parents being left to discipline their son, the justice machinery swung into action, the boy was prosecuted and lost his training scheme spot.
Any involvement of the authorities is the choice of his clients, said Reuther.