Smile Dog origin and original story

When was Smile Dog made? The smile.jpg story appeared on forums and imageboards around 2008. Its author is not reliably documented, and the text was reshared and edited many times.

The story in brief

A narrator investigates a woman, Mary E., said to be haunted by an image of a smiling dog; the creature demands that viewers "spread the word". The story borrows from chain letters and cursed-media fiction.

Smile Dog is a fictional creepypasta (internet horror story). No real image causes nightmares or harm.