This measures the rate and strength of your horse's heartbeat. Normally, a resting horse has a pulse of 38 to 40 beats per minute. When exercising, a horse's maximum heart rate can exceed 180 beats per minute.However, in resting horses, a heart rate over 80 can be a sign of a serious problem.If a calm horse has a pulse that is consistently over 60, it can also be a problem.hen exercising, a horse's maximum heart rate can exceed 180 beats per minute. However, in resting horses, a heart rate over 80 can be a sign of a serious problem. If a calm horse has a pulse that is consistently over 60, it can also be a problem.