A resting adult horse should have a heartbeat range from 28 to 48 beats per minute. More than 60 beats per minute in an adult resting horse is abnormal and anything over 80 is really bad. Care should be taken as foals have a quicker heart rate of 70 to 90 beats per minute.Horses doing strenuous exercise can reach 200 beats per minute but this is rare and extreme.f you know what is normal for your horse you will be able to see changes at an earlier stage rather than waiting until these vital signs have moved into the âextremely badâ range. You will need a watch with a âsecondsâ hand or better still a stopwatch. Heart Rate.