What is Aneurysm?
Aortic aneurysm is the most common type of aneurysm in horses. The aorta is the main artery that transports oxygenated blood from the heart to other arteries. When the aorta ruptures, blood fills and compresses the horse’s heart, and sudden death occurs. The aorta can sometimes rupture within the heart; this is called an intracardiac rupture. The aorta blood then flows down into the ventricle septum (the wall that separates the chambers of the heart). Intracardiac rupture will cause the horse to experience acute colic and rapid heartbeat.
An aneurysm happens when the wall of an artery weakens and causes the artery to become enlarged. The aneurysm becomes a large bulb (balloon) that will eventually rupture and cause internal bleeding.
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Symptoms of Aneurysm in Horses
- Sudden breathing difficulty
- Tissue death
- Blood in the urine
- Abdomen pain
- Muscle tremors
- Exercise intolerance
- Edema on the neck
- Aortic aneurysm is also called ruptured aorta, and is the most common aneurysm in horses
- Cerebral aneurysm is not very common in horses
- Intestinal aneurysm is due to Strongylus vulgaris, these aneurysms rarely rupture
- Venous aneurysm is a widening and bulging of a vein
Causes of Aneurysm in Horses
- The larvae of the bloodworm, Strongylus vulgaris can cause inflammation of the artery walls
- Aneurysm is secondary to other heart conditions or diseases
- Congenital defect or degenerative disease can weaken the wall of the arteries
Diagnosis of Aneurysm in Horses
The equine veterinarian will take a thorough medical history of your horse. He will discuss what clinical signs you have observed. The veterinarian will then perform a physical exam on your horse which may include taking the horse temperature, listening to his heart and lungs, a rectal exam, and palpation of the abdominal and chest area. The veterinarian may recommend a complete blood count (CBC), urinalysis, and fecal exam. Diagnostic tests that the veterinarian may suggest are electrocardiogram (EKG), x-rays, ultrasound and an echocardiogram.
Echocardiography, also called an echo test, may be able to show the early stages of an aneurysm. Echocardiography is able to take two and three dimensional images of the heart. Doppler echocardiography can also help determine the blood flow patterns, direction, and the velocity of blood circulation. It is better to not sedate the horse for the echocardiography unless he is extremely anxious. Sedatives can influence the body’s blood flow, which may hinder the results of echocardiography.
Treatment of Aneurysm in Horses
Treatment of aneurysm in horses will depend on the cause.
If your horse is diagnosed with parasites (bloodworm) he will need to be dewormed. The veterinarian may recommend the dewormer Ivermectin; it not only kills the larvae in the blood but also the adult bloodworms in the stomach. Make sure to follow the veterinarian’s instructions on the dosage amount and how often to administer the dewormer. The dewormer will get rid of the parasites but the aneurysm will still be present. Antibiotics may also be prescribed. Aneurysms due to Strongylus vulgaris do not typically burst.
It is important to follow the treatment plan given to you for your horse. Aneurysms carry a guarded and grave prognoses. Once an aneurysm has been found, the horse should have limited exercise, to help lower the possibility of it rupturing. Depending on the size of a venous aneurysm, the veterinarian may recommend surgery. Diuretics and anti-inflammatory medications may also be prescribed.
There are no medical cures for horse patients with intracardiac ruptures. Horses that have an intracardiac rupture may develop secondary heart failure, and may only have a few weeks to live. The veterinarian may suggest humane euthanasia.
Recovery of Aneurysm in Horses
If your horse underwent surgery, the surgeon will give you post-operative instructions. Your horse will be given pain medication and antibiotics. Follow-up visits will be needed to check on the horse’s progress and to remove sutures.
If the patient had Strongylus vulgaris, it will be important to prevent re-infestation of your horse. Regular cleaning of the stalls, deworming the horses, and frequent removal of feces from the pasture, are recommendations to prevent an infestation. Most veterinarians suggest deworming horses every two months. If you have any questions on how often to administer the dewormer; ask your veterinarian what he would recommend.
In patients with intracardiac rupture, prognosis will depend on the size of the rupture. The horse will need to remain on diuretics, antiarrhythmic medications and have limited exercise. The patient may live comfortably for a few weeks or possibly a few months.