A family has been reunited with their dog nearly four years after she vanished thanks to a microchip - and the kindness of a stranger.

The Metcalf family, from Raleigh, North Carolina, thought they would never see their beloved pet, nine-year-old Cassie, again after she wandered off while staying with another relative.

Although they have no idea where she spent the last few years, what they do know is she wandered into the neighbourhood of Cheryl Smith two weeks ago.

The concerned resident of Gaston County, which is more than 190 miles from Raleigh, noted the dog did not have any collar or identifying tags - but she refused to take her to a shelter.

Instead, she took Cassie to numerous veterinarians in the hope one would have records for her and lead them to her owner.

They discovered she was micro-chipped and, although the Metcalf family had changed their address, managed to track them down in Raleigh with the help of the Gaston County animal shelter.

'I felt like if it was my dog I would want someone to do that for me,' Smith told WBTV.

She called the family to say they had found the dog - and found Cassie's previous owners in shock.