Aneurysm in Horses

Aneurysm in Horses

An aneurysm is an abnormal ballooning of a weakened arterial wall in the body. If the ballooning becomes big enough, it will burst, leading to massive hemorrhaging and death. An aneurysm has no warning signs; therefore most horses die of the condition before it is diagnosed.

Symptoms and Types

The main type of aneurysm seen mostly in horses is the aortic aneurysm. Aortic aneurysms occur when a portion of the aorta, the large artery that comes straight from the heart, develops a thin wall. If enough pressure is placed on this thin area (such as during a time of extremely high heart rate), this area may burst, leading to almost instantaneous bleed-out. This is seen most commonly seen in Thoroughbred racehorses, as their heart rates and blood pressures are extremely high during a race. Cerebral hemorrhages from a ruptured aneurysm (also called a stroke) are not as common in horses as they are in humans.

Signs of a ruptured aortic aneurysm are dramatic and include sudden collapse, pale mucous membranes, and death. 


Diagnosis is usually made post mortem (after death). There are no warning signs of an aneurysm, and once it bursts, the horse cannot survive.

post mortem

An examination that occurs after the living thing has died


A large blood vessel that transports blood out of the heart.


The name of the main artery that starts in the left ventricle of an animal’s four chamber heart.


The enlargement of an artery; usually shaped like a bubble or balloon.

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