Aneurysms in Dogs

Aneurysms are a bulge in a blood vessel, usually an artery, caused by a weakening of the walls of that blood vessels. This can be caused by conditions such as congenital diseases, physical injury to the artery, or atherosclerosis. As long as aneurysms do not rupture, these bulges in the arteries can sometimes remain undetected in canines for years, particularly in locations such as the brain and the abdominal aorta. If an aneurysm bursts in the brain or in the aortic arteries coming from the heart, the results can be dire. In many cases, aneurysms can also cause dangerous blood clots to form.

Aneurysms are bulges that develop in the blood vessels due to a weakness that occurs in the vessel walls. Aneurysms usually arise in the arteries and can be extremely dangerous when they rupture.

Symptoms of an aneurysm in dogs depend on where in the body they are located and sometimes show no symptoms until after they rupture. Symptoms of a cerebral aneurysm are generally non-existent until the vessel ruptures. When the blood vessel does break you may see:

• Bleeding from ears or nostrils
• Blue skin
• Loss of consciousness
• Rapid breathing
• Seizures
• Sudden death
• Unusual posture

Symptoms of an aortic aneurysm can cause some chest, back, or abdominal pain, but more often than not, there are no symptoms prior to rupture. Rupture can cause:

• Blue skin
• Bulge in the chest
• Coughing
• Nausea
• Pain in the chest or back
• Shortness of breath
• Sudden death
• Vomiting

Other aneurysms can occur anywhere in the body and if symptoms do arise with or without a tear they may include:

• Cold limbs
• Lack of a pulse
• Leg pain
• Limb pain or weakness, particularly after exercise
• Paralysis of limb or limbs
• Pulsating lumps

Types

A cerebral aneurysm is a weakened blood vessel that is located in the brain, it is exceedingly rare that a cerebral aneurysm is detected before it ruptures, and brain aneurysms that rupture are usually fatal. 

A peripheral aneurysm refers to an aneurysm that occurs anywhere other than the brain or heart. These can take place in any part of the body but are most common behind the knee, in the groin area, and the carotid artery in the neck. 

An aortic aneurysm affects the aorta and can be found either at the spot where the aorta extends into the chest (thoracic) or where the aorta narrows towards the dog’s hips (abdominal). The abdominal aneurysms are slightly more common than the thoracic.

The causes of an aneurysm are numerous, and some reasons are unique to a particular type of aneurysm. Elements that can contribute to any kind of aneurysm in your pet include:

• Atherosclerosis
• Fungal infections
• Injury
• High blood pressure
• Obesity
• Parasite infestation
• Undetected congenital conditions

There also seems to a link to familial aortic aneurysm in the Leonberger breed, and head trauma can contribute to a cerebral aneurysm. In humans, cigarette smoke can be a significant contributing factor in developing abdominal aortic aneurysms.

When an aneurysm is located in the brain, the lack of symptoms generally means that the diagnosis is made post-mortem as the rupture causes cerebral hemorrhage, leading to an extremely rapid decline or instant death. On extremely rare occasions an aneurysm in the brain is caught when imaging the brain for another disorder.

Aneurysms of the aorta are often diagnosed using imaging techniques such as MRI, transthoracic echocardiography, or transesophageal echocardiography. 

As peripheral aneurysms are also less likely than the others to rupture they may continue undetected for quite some time. If the bulging vessel is located near the skin, a pulsating lump may be detected by touch. In many cases, your dog's doctor will image the area by ultrasound to further investigate.

Cerebral aneurysms are almost universally fatal, sometimes within seconds. Treatment for aortic aneurysms is also extremely limited. Surgery to repair the aorta may take place, but depending on the placement and the dog’s condition, it is often not feasible. Studies are being done on aneurysms using two embolization gels to repair leaks and promote healing, but the testing is still in its infancy. Aneurysms in the legs and other areas may be left untreated if they don’t appear to be causing a problem. Many peripheral aneurysms remain static, although they will be monitored by your veterinarian.

Dogs who develop aortic or peripheral aneurysms are also at a higher risk of developing blood clots. Clots that form at the site of an aneurysm may travel to other parts of the body before lodging in a blood vessel. If this occurs, blood flow past the clot can be interrupted and can cause severe damage to the tissues or organs that are starved of blood, beyond the clot. As this condition can also potentially be fatal, your veterinarian may want to take steps to reduce clotting as well.

The prognosis for a dog with an intact aneurysm is guarded. An aneurysm can rupture at any time, or it may never rupture. If it does burst the expected recovery depends on where the weakness is located. When either cerebral or aortic aneurysms rupture, the prognosis is poor, and even a rupture of a peripheral aneurysm can be fatal if it occurs in an artery like the femoral artery, which bleeds out quickly. If your canine companion exhibits any of the signs of an aneurysm, getting them into the clinic as quickly as possible gives them the best shot of survival.