This is a quote from one of my assigned reading cardio textbooks:
"...a strong emotion can lead to precipitous hypotension with syncope (i.e., fainting). Conditioned reflexes can also elicit cardiovascular responses. For example, it is possible, by reward conditioning, to train an animal to increase or to decrease its heart rate."
One more thing to consider when training an endurance horse.....
Two days of heavy rains, flash flood warnings
10 hours ago