Although acquired heart disease is uncommon in horses, when it develops it is accompanied by a reduction in exercise capacity and shortness of breath and the horse may collapse with congestive heart failure.
Importance of heart health in horses
A horses heart may be the most important muscle in its entire body, since it is responsible for the rapid delivery of nutrients and oxygen to all of the horse's tissues and organs.
Horses seem to be able to compensate for a diseased heart for many months or years without signs of heart failure. In most cases, the heart muscle is weakened and begins to lose the ability to provide adequate circulation to meet the body's needs.
The chief causes of heart disease in horses are bacterial endocarditis, pericarditis, cardiomyopathy, myocarditis, valvular disease, and congenital heart defects. Bacteria, viral infections, and long-term use of anabolic steroids have been associated with severe heart damage.
According to Anne Desrochers DMV, Diplomate ACVIM, a horse’s heart may be the most important muscle in its entire body. As the pump for the cardiovascular system, which includes the heart and a closed system of blood vessels called arteries, veins, and capillaries, it is responsible for the rapid delivery of nutrients and oxygen to all of the horse’s tissues and organs.
In addition, the cardiovascular system plays a crucial role in the elimination of waste products, distribution of hormones, immune response, blood clotting, and body temperature regulation.
Heart disease can affect horses of all ages and breeds. It can be congenital and present at birth or acquired later in life. The most common abnormalities involve the valves and muscle of the heart. Cardiac problems can manifest clinically in different ways, including poor performance, exercise intolerance, presence of a heart murmur, irregular heartbeats, distended veins, peripheral swelling, poor growth, weakness, or collapse.
Horse owners should be aware that over time the valve leaflets in the equine heart change and become stiffer as a horse grows older. This change can lead to leaks in the valve and development of a heart murmur.
The most common age-related murmurs are those of leaky mitral or aortic valves. The presence of a murmur in and of itself may not necessarily be cause for alarm but it must be monitored for change over time. A heart murmur is something that a veterinarian should check for during an exam.
If there is any uncertainty as to the severity of a murmur, the size and velocity of the leak can be measured by a cardiology ultrasound. If the murmur changes dramatically, becomes very loud, or the horse develops signs of heart failure, then the animal should be re-evaluated by ultrasound
The importance of the heart cannot be overstated and any disease affecting it should be promptly diagnosed and treated by a veterinarian.
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