We'll first use the stethoscope to count the number of heart beats per minute. Some promising individuals with bigger, stronger heart muscle only need to pump blood 26 -30 times per minute. These are good prospects for sports requiring sustained cardiac output. Place the diaphragm of the stethoscope on the horse s left chest wall in the girth area just behind an slightly above the point of the elbow. Count for exactly 15 seconds, then multiply the result times 4 to get the rate per minute.
Horses have an absolutely amazing cardiac capacity.
At maximum work, they can multiply their resting pulse rate by a factor of 8-10. In other words, an athlete with a resting pulse rate of 26 BPM could work at maximum exertion for a short period with a heart rate of 260 beats per minute. Think what would happen to your own heart if your resting pulse rate of 60 went up to 600 when you ran. A conditioned horse's heart rapidly drops back towards the resting rate the very moment he stops working. Most endurance riders find that no matter how steep the hill they just went up, or at what speed, it is hard to catch the heart rate at higher than 120 or 130 BPM after dismounting.