Running for your life

Excuse the brevity because this isn't my fortay. The question i pose is, why after the Kentucky Derby did they have to kill the horse (eight belles) that broke his two front ankles, and on the track at that. Like i said i do not know alot about horse physical therapy but i suppose there could have been some sort of horse cast they could have given the philly, right? I do know that he needs to be able to walk but im sure with modern technology and money they could manufacture something. Or did they have to kill her because the horse could no longer be a race horse and make money, I don't know, im just throwing that out there. Oh yeah, and here comes PETA...