It is hard on the horses. Horses aren't really meant to be run this hard for this long, doing so really takes it's toll. And these races are long, the shortest is the second leg and it's still 1 3/16 which is pretty long. When these horses are done, if they weren't on the drug Lasix they would be probably be bleeding from the nostrils from hemorrhaging in the lungs (
http://en.wikipedia.org/wiki/Exercise-i ... hemorrhage). Racing is very hard on horses, this is why they have very few training runs where they really blow it out between races, and when they do it will typically be 1/2 mile or so. When Secretariat pulled away from Sham at the Belmont in '73, Sham had also ran the two previous races.
But having said that, if Secretariat or Seattle Slew or Affirmed or most any other Triple Crown winner spun out of the last turn like California Chrome did today with room to run, the other horses would have been getting a face full of dirt kicked in their faces down the stretch. Yes it's true that fresh legs are an advantage, but if Chrome were a true champion he would have won today.
The fact is, California Chrome was the best of a lackluster bunch of horses. I was hoping for him because of the story, but he is not a great horse. There have been many horses that lost at Belmont in the last leg that were a better horse than this horse.
I think the owner has a gripe, and I understand his disappointment and all, but it would have been nice if he could have bit his tongue. I'll bet if Penny Chenery had lost with Secretariat, she would have lost with grace.