From sharp-toothed sheep killer to disciplined herder, the transformation of a dog trained in Bingley is the subject of a BBC documentary tonight.

In just 12 weeks, Barbara Sykes, a dog trainer at Mainline Border Collie Centre, at Golcar Farm, in Bingley, has turned around the life of an unwanted beardie collie called Herbie.

The progress of Herbie, who has learned to save his teeth for munching his dinner instead of attacking sheep, was filmed by BBC 2 for The Natural World programme.

It follows the once-violent canine from being picked up from an RSPCA centre in Leicester, to running around as a rehabilitated sheep herder, saved from an uncertain future.

The programme documents how a canine's natural instincts can be harnessed to correct problem pets into working dogs, and also charts the tale of Holly, a bloodhound in America.

Holly was turned away by six families because of her hyperactivity and destructive behaviour.

Mrs Sykes, who specialises in canine behaviour, said: "Herbie was an RSPCA dog and had been really wound up with toys in his early years, was terrorising sheep and ended up being sold through a cattle auction.

"He had gone too far to be re-homed and farmers didn't want a dog which could kill their sheep. When he came to us he could shred a football. The only other option was euthanasia.

"His transformation was all done through our Thinking Like Canines technique, using his own instincts to re-train him. It is purely and simply based on body language and building up a relationship between dog and trainer. There are no choke chains involved, it is all about getting inside his head. Herbie can now go into a flock of sheep and never uses his teeth."

Mainline Border Collie Centre is a training centre for sheepdogs and it runs courses for dog owners to train their pets to be more obedient. The re-born Herbie now lives and works at Golcar Farm and can control a flock of up to 80 sheep.

The show airs at 9pm on BBC 2 and is billed as The Bloodhound and the Beardie.