Eight emaciated horses were turned over to Spot-O-Faith Horse Rescue in Pasco.
The non-profit doesn't plan to report the case to authorities since the former owner voluntarily turned the horses in.
Spot-o-Faith's director says it's the worst case she's seen since last summer.
"I really have no idea why someone does not feed - choose to feed - their horses. Some of these horses have shoes on them, so they've been ridden all summer. Obviously, they just haven't given them groceries," said Spot-O-Faith Director Linda Christiano.
The rescue plans to rehab the horses and find them new homes.