Teri is alerted from time to time about horses being held at slaughter pens. They are confined until there are enough horses to fill a cattle trailer to ship them to Canada or Mexico to be slaughtered for their meat.
These are not old, diseased horses to begin with because, practically, they’d never survive the trip. Horses are collected by “kill buyers” who drive around the country buying horses, inexpensively, at auction. Many of these horses are young, trained, have been someone’s “pet” who couldn’t or didn’t want to keep them any more. Some are pregnant mares, some mares with foals.
The abuse these magnificent animals suffer throughout the slaughter process, from auction to feedlot to transportation, has been closely documented by Animals Angels.
More information about horse slaughter and the US can be found here (if you have the stomach for reading more).