This kind of gruesome death is likely to be described using phrases like:
* Drawn and quartered: This is a historical form of execution where the victim is tied to four horses and the horses are then driven in opposite directions, tearing the body apart.
* Torn apart by horses: A more direct description of the action.
* Dismembered by horses: This emphasizes the separation of the limbs.
It's important to note that this is a very graphic and disturbing image, and it's not something that is often discussed in polite conversation.