Big-Hearted Horses

A horse that gives his best effort for his rider, sometimes surpassing what he has been expected to achieve, might provoke the comment, “That horse has a lot of heart.” Horses do have very large and powerful hearts that are able to supply a great volume of oxygenated blood to working muscles, simultaneously removing the waste products of exercise in an efficient manner.

The Horse Report, a publication of the Center for Equine Health at the University of California, Davis, mentioned these interesting facts about the equine heart.

• A 1000-lb horse has a heart that weighs about eight to ten pounds and is the size of a large melon.
• At rest, a horse’s heart pumps about 7 to 10 gallons of blood per minute. The human heart pumps about a quart of blood in the same time.
• For a horse with an average lifespan, its heart will beat almost 640 million times throughout its lifetime.
• The best place to listen to your horse’s heart is on the left side just behind the elbow. You may be able to feel the heartbeat by placing your hand in this area. Because the horse’s heart beats more slowly than a human’s, be sure you are counting each “lub-dub” as only one heartbeat, not two. Normal rate for a horse at rest is between 28 and 42 beats per minute. It may be somewhat faster or slower and still be within the normal range.
• A veterinarian in the 1880s was the first scientist to describe normal heart sounds and their origins in a horse. This information was later extrapolated into human medicine.
• The incidence of heart disease is low in horses.
• Some benign heart murmurs occur in horses, but many are not a cause for concern.
• Cardiac ultrasound can reveal problems such as heart wall defects, leaky valves, or constrictions in a blood vessel.
• Some equine heart problems can be detected by using heart monitors or examining cardiac enzymes such as troponin to detect evidence of heart muscle injury.
• Human pacemakers have been used in some horses and donkeys to regulate abnormal heart rates.