A 13-stone family pet helped save a young boy's sight, his owners claim.

The parents of Mark Cannon from Strathaven, South Lanarkshire, say their French mastiff Alfie always insisted on walking and sitting by the youngster's right side.

The dog's behaviour seemed like that of a guide dog, so Mark's family made him an appointment with an optometrist.

Mark, five, was then diagnosed with an astigmatism in one eye. Medics told mother Sharlene and father Mark their son could have gone blind if the problem had not been discovered when it was.

He now wears a patch to strengthen his weak eye and his parents believe their son's sight was saved by his best friend.

Meanwhile, Mark and Alfie are as inseparable as ever.