Police in Northumbria have started using sniffer dogs on the streets to spot drug users among clubbers. The dogs are referred to as Passive Alert Narcotics Detection Animals (Pandas). Sergeant Dave Surtees said: "Basically, the dog is trained to smell the air around a person and detect if drugs are there. "The dogs will indicate drugs on people for up to 48 hours . "So if a person has had cannabis in their pockets, two days later, if they have the same coat on and it has not been washed, the dog will pick it up. "They are very good at what they do and have never failed yet to indicate somebody."