Family and friends had an idea a month ago to send the 7-year-old Wisconsin girl cute pics of their pups with well wishes as though they were penned by their doggies.
They hoped it would cheer up Emma and her family after learning she has a rare form of brain cancer - one that has no cure. But no one expected what would happen next.
The world got wind of the plan
Within days, what was just a friends-and-family project went global.
"It got posted onto Facebook a couple of times. Next thing you know it went viral," her dad, Geoff Mertens, told CNN.
"Some reality TV star from New Jersey shared it on her Instagram page - The Real Housewives of New Jersey," he said.
"Don't ask me who. I've never seen it but I'm sure she's just a big dog lover. Then (practically) every dog site's Instagram page in the country shared it," he said.
He told CNN Emma has gotten letters from as far away as Japan, Australia and Venezuela.