With a pile 10 feet tall the weight can compact the core of the material. Make sure this is not happening. Drying is a problem if you blow air in. If the pile is porous enough, just leaving them open to the ambient air may be enough to cause a circulation. Static piles can work very well if kept from compacting too much.
Moisture is also of concern in horse manure.
It usually is on the dry side. One problem with all this advice is that it will be a year before you will know if it is any good or not. Composting is as much art as it is science. Like the difference between a cook and a chef. The three thermometers I am using now have a 20 degree spread between them .