This just in from the University of Pennsylvania:
"Barbaro has had a significant setback over the last 24 hours. He became acutely more uncomfortable on his left hind foot. The foot cast was removed and some new separation of the medial (inside) portion of his hoof was found. This required some additional debridement (removal of the damaged tissue) last night.
"He is being treated much more aggressively at this time for his discomfort. He is continuing to eat well and is otherwise stable."