The 5-year-old buckskin miniature gelding was taken in the middle of the night or early morning hours of April 25, the horse's owner, Brittney Cunningham, says.
Cunningham said his pasture door was open when she came out to feed him.
She added that the chain link fence was cut where the horse napper led him out on the street and into a trailer.
A neighbor reported seeing a black Dodge Ram 1500 with a small white cargo box trailer at the scene.
Cunningham is trying to spread the word with flyers and posters, hoping someone knows where her horse is.
"My best chance is social media and getting the word out. Horse community, letting as many people as I know as possible. So that's the best way that I'm going to be able to find him."
Rumble has a white crescent on his forehead, which is his most distinguishing mark.
There's a $500 reward being offered by Cunningham for anyone who can bring the horse back home.