My horse ate a plastic bag, what do I do?

Looks like he swallowed it and I don't know where to go from here... just waiting for the vet to call back
Answers:
Vet may have to tube your horse with mineral oil, so that the plastic bag does not cause an intestinal blockage.
If the horse shows any signs of colic before the vet gets there (nipping at his belly, wanting to lay down, sweating, groaning, straining to move his bowels), keep him on his feet and walking.