Here is the blurb from Iowa regs:
Retrieval and Waste of Game
While taking or attempting to take game or
furbearing animals, you cannot abandon the injured
animal without making a reasonable effort to retrieve it
from the field. You cannot leave a usable portion of the
game or furbearing animal in the field. “Usable portion”
in this instance means the following: 1) for game, that
part of an animal that is customarily processed for
consumption; and 2) for furbearing animals, the fur or
hide of the animal.
I would guess that it is fairly standard for most states.