A dog owner has been ordered to pay compensation after the animal was judged to be out of control.
David Moyse, 37, of Greig Walk, Corby, pleaded guilty to being in charge of a dog which was dangerously out of control after an incident on October 10 last year.
German shepherd Donny was in the back of a vehicle in Finland Way, Corby, when it heard two people walking nearby.
When the door was opened it ran out and bit Alaric Marshall, 18, on the thigh. Mr Marshall then jumped over a fence to get away.
Mr Marshall went to a nurse the following day and was found to have 5cm of bruising. He then reporting the matter to police.
Richard Insall, prosecuting at Wellingborough Magistrates Court, said: "Mr Marshall had a nasty shock and it was an unpleasant experience. Fortunately, there was no lasting mark."
Val Blow, for Moyse, said Donny had trained with the police and when the dog heard noises nearby it instinctively reacted to them. She said: "This was an unfortunate coming together of circumstances."
Mr Moyse, who worked as a security officer for Corby Council, was using the dog to help him patrol the area.
He was fined 100 and ordered to pay 200 costs.