Originally Posted by Void
There is no science to back that statement, all Animals have warm-blood, if anything colloquially they are known as "hot-blooded" horses.
What they are referring to is them being hot blooded and having a thin skin to handle the heat better. And that is very useful for a high energy athletes that lives in a heated barn as nice as some houses. But this makes them have a very poor cold tolerance. In my home state of Kentucky, I have even seen trailer loads of racehorses headed to Florida for the winter and there are races do there too.