This is the touching moment a hero passerby rescued a pet dog stuck in sinking mud.

Pet lover Jans Issara and her boyfriend were walking their own pooches along the bay when they noticed the stricken animal stranded in the sludge during low tide in Krabi province, Thailand, on August 12.

The couple stopped by, climbed down the bridge where the boats were docked, and helped pull the dog's legs from the thick mud.

Footage shows Jans' boyfriend crossing the mud on a board before removing the stuck dog's limbs from the ground.

Jans said: 'We were worried something might happen to the dog because he's big, and it clearly would have been difficult to carry him up.'

The dog was returned to his owner, who lives nearby. He was unhurt in the incident.