She has unearthed the possibility that there was a traveling horse and pony show in Sheboygan in the summer of 1900, and that a storm might have disrupted the show and allowed some of the horses to escape, she said.Someone else has suggested that the animal had been trained to play dead, or had been given an "elixir that calms the most nervous horses."
She also examined the appearance of the street in the picture and thinks there may have been some kind of natural disaster.
"I think … there is something wrong with the street," she said. "It looks like there's been a flood — it looks like the pavement has been removed." [Link]