We often talk about certain horses “having a big heart,” because they give all they can when asked to run or jump. But a horse’s heart is more than a metaphor.
The heart can’t be discussed in isolation; it is just one part of the cardiovascular system, and it’s not the driver – it’s the slave. Ontario Veterinary College professor emeritus Dr. Peter Physick-Sheard says, “The heart doesn’t control the system; instead, it responds to the change in pressure in the animal’s arteries, which in turn is under the control of tiny valves in the smallest of blood vessels.”
Causes of sudden death
When all the valves open wide to allow blood to flow into the muscles, as will happen when the horse is racing, jumping, or otherwise exercising intensely, the heart has to work hard to maintain the correct blood pressure. Horses don’t have “heart attacks” the way humans do. But they can sometimes die suddenly, especially after strenuous activity such as racing or eventing, and while an aortic aneurysm may often prove to be the culprit, the cause isn’t always known. These sudden deaths are thankfully rare, but usually involve some aspect of the heart or cardiovascular system.