This is the heartbreaking moment a grieving pet dog who misses his owner stared at the old man's portrait.

The seven-year-old male pooch named Guer lived with grandfather Gong, 75, since he was a puppy until the patriarch died last year due to sickness in Bangkok, Thailand.

Guer was then left in the care of old man Gong's close relatives but the family said the dog remained grieving and still misses him everyday.

Footage shows the dog Guer standing in front of his owner's old bed while looking at his pictures on October 19.

Gong's daughter Sandguen Rungruaysub said: ‘We always find him in this room, just looking at the portraits. It breaks our hearts whenever we find him just looking at his pictures.

‘We chose to keep his room the way it was when he was still here. We believe it keeps his memory alive.'

Sangduen added that the dog would sometimes be sleeping on the old man's bed and would stay there the whole day.

She said: ‘Whenever Guer is nowhere to be found, we know he hangs out in the room and sleeps on grandpa's bed. He was an affectionate dog.'

Sangduen added they will be doing a Buddhist ceremony and burn incense for grandpa Gong's spirit and remember him.

He said: ‘Our relatives told us to burn incense since it's near his death anniversary. We still miss him every day and so does his dog.'