Excellent question.? The answer is absolutely, "Yes!"? You can over condition your horse and put him in danger that way just as you can by under conditioning.? It used to be more typical, I think.? Horses came to competitions worn out and too thin.? They left their best rides out on the conditioning trail.? While there are more people who may under condition, we still occasionally see over conditioned horses.? It's a fine line, of course :)