A teenage boy has been found guilty of stabbing a police dog and its handler during a suspected robbery.

The 16-year-old plunged a 12-inch knife into German Shepherd Finn narrowly missing the dog's heart.

Finn later needed a four-hour operation, including having two sections of his lung removed, after being stabbed in the body and head.

The dog's handler, Pc David Wardell, suffered a stab wound to the hand after running to help Finn.

Pc Wardell broke down in tears as he described the moment he feared for his life as the teenager brandished the "largest knife" he had ever seen.

The boy, who admitted being in possession of a knife and imitation firearm, claimed he was acting in self-defence after fearing being bitten by the animal.

But District Judge Jo Matson found the boy guilty of actual bodily harm, as well as criminal damage to the dog.

Finn the dog has since returned to the force after making a recovery and has subsequently retired from service, Hertfordshire Police said.

The youth will be sentenced in Bromley, south London, next month.