What is Defect of the Ventricular Septum?
Small and moderate defects of the ventricular septum have a good prognosis and show few or no symptoms. Large defects, however, have a grim prognosis and exhibit symptoms such as heart failure, cyanosis, and the development of Eisenmenger’s syndrome. There are different treatment options, depending on the size of the defect. Some options include medicinal supplements, exercise restriction, and surgical treatment of the defect, though surgical treatments are expensive and rare.
A defect of the ventricular septum refers to a hole in the septum (the muscular wall inside the heart), which divides the right and left ventricle. This can occur at varying stages of the development of the heart, which starts out as one tube before birth and gradually becomes four chambers during normal growth throughout pregnancy. The result of this hole in the septum is abnormal blood flow in the heart. These defects are most commonly found in the membrane of the septum. Size and impact on blood flow varies. In most cases, the abnormal blood flow that results from ventricular septal defects occurs because of an abnormal pressure and changes in pressure between the two ventricles.
Ventricular septal defects are essentially holes in the wall of the heart that create abnormal blood flow in the heart. Depending on the severity and size of the defect, symptoms and prognosis will vary.
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Symptoms of Defect of the Ventricular Septum in Dogs
Symptoms vary depending on the size of the defect, ranging from no apparent symptoms at all, to eventual coma and death.
- Heart murmur
- Heart failure
- Cyanosis (bluish skin, especially in large defects of puppies – if this symptom exists, prognosis is grim)
- Inability to exercise
- Shortness of breath
Defects of the ventricular septum are identified primarily by the size of the defect. Small and moderate defects may exhibit no symptoms at all, while large defects may result in Eisenmenger’s syndrome, pulmonary circulation, and/or death.
- In small defects, there is typically a loud heart murmur and few symptoms exist. There is usually no sign of disease on X-rays. Color Flow Doppler echocardiography can assist in diagnosing small defects. This will highlight flow of blood by use of reflections from moving blood cells. Blood flow will accelerate toward the defect, and near the defect the speed of blood flow will become greater.
- In moderate defects, a loud heart murmur is also present. While moderate defects may not result in symptoms, mild heart failure may develop early in their life. X-rays may show cardiomegaly (an enlarged heart) or pulmonary circulation (increased blood flow to lungs). A regular echocardiography may allow for diagnosis in moderate defects, though a Color Flow Doppler Echocardiography will also assist if an echocardiography is not sufficient.
- Rare in animals, puppies affected by large defects will likely die a few weeks following birth from heart failure. For those that last longer than a few weeks, they may still exhibit heart failure, as well as Eisenmenger’s syndrome (a left to right shunt, caused by congenital heart defects in the heart of a fetus) or cyanosis (skin becoming blue from lack of circulation/poor oxygenation of blood).
Causes of Defect of the Ventricular Septum in Dogs
There are no real known causes of ventricular septal defects. In the English bulldog, Keeshond, and English Springer Spaniels, inheritance may have a hand. In these breeds, either parent can pass the gene along to offspring. Dogs with a small defect that has little to no impact on their lives may produce offspring with defects ranging from small to large, as well as offspring with no defects at all.
Diagnosis of Defect of the Ventricular Septum in Dogs
When you arrive at the clinic, the veterinary team will be ready to make a diagnosis. Be sure to relay all relevant signs of a problem, such as appearance of your pet during times of exertion, recent behavioral changes you mat have noticed, and general demeanor. Your veterinarian will do a thorough physical examination, listening to the heart and checking for the rate and sound. Other diagnostic tools may include the following.
- Blood tests
- Chest x-rays
- Ultrasound of the heart
- Color Flow Doppler echocardiography
Treatment of Defect of the Ventricular Septum in Dogs
Treatment options depend largely on the size of the defect. Surgical correction is rare due to availability and cost, though it remains an option.
- Medications to support the heart
- Vasodilators to reduce vascular resistance
- Medications to reduce congestion in lungs
- Special diet
- Restriction of exercise
- Cardiopulmonary bypass in order to surgically close the hole (this is a limited treatment option, due to availability and cost)
- Percutaneous transcatheter closure
- Pulmonary artery banding
- Phlebotomy may be used to relieve clinical signs, though it doesn’t treat the actual condition
Recovery of Defect of the Ventricular Septum in Dogs
Ultimately, post-treatment recovery and management will depend largely on the size and severity of the defect, as well as any accompanying problems. Medications may be administered to help reduce stress to the heart. In addition, heart-healthy diet specifications may be made, as well as exercise restricted. If the dog suffers from a small or moderate defect, they will likely live a fairly normal and healthy life. In severe and large defects, or defects where other conditions affect overall well-being, the dog is less likely to survive. Dogs that are diagnosed with ventricular septal defects should not be bred, as the cause of these defects is believed to be genetic.