Forget heart -- does your horse have the spleen to win?

This is a digested version of an already short article Horse Science: What Makes a Kentucky Derby Winner By Bjorn Carey, LiveScience.com
Dr. Kenneth McKeever, researcher at Rutgers University, and Dr. Eric Birks of the University of Pennsylvania have uncovered physiological adaptations that help horses run faster. These are summarized below:

• First of all, horses breathe only through their nostrils, which are situated on their snout so that they are not exposed to dust. Breathing through the mouth would make them prone to inhaling dust.
  
  
• Horses at a gallop only inhale as they are bringing their legs forward. This helps them expand their lungs fully, without pressure/interference from their large gut. If the horse inhaled as his legs are landing, the forward pressure from the gut would limit lung capacity. A side effect of this fact is the theory that the longer a horse's stride, the greater the capacity to inhale
  
  
• When the horse starts its gallop, the hind leg muscles clamp down on the spleen -- a relatively large organ in the horse's rump -- "like a bagpipe and squeeze all that extra blood into the circulation system," says McKeever. The blood takes extra oxygen to the muscles, and the beneficial effects last for about an hour after exercise.
  
  
• When the spleen does its thing, the horse's blood gets a lot thicker, which would significantly affect some animals --- but not the horse. Their hearts are larger and far more powerful than other animals

But it is notable that the researchers maintain that having this knowledge does not make us any better able to predict race winners. McKeevy reflects on his experience observing and testing horses, and he feels that the desire to run may be the most important trait of all. Some horses just want to go. I guess the heart is more important than the spleen after all....