Images of Vida soaked in claret shocked the country and now there are growing fears that the injury sustained is at risk of becoming infected, potentially putting its life at risk.
Two of the animals underwent surgery overnight on Wednesday and were said to be in a serious condition by defence minister James Cartlidge on Thursday morning.
Five people, including three soldiers riding the horses, were injured in three separate incidents during the six-mile rampage across London on Wednesday that lasted two hours.
Army bosses have claimed it is too early to know if Vida and Quaker, the runaway Household Cavalry horses that rampaged through central London will ever return to active duty.