Disease Description: A malformation of the dividing wall between two chambers of the heart, usually resulting in a hole which then causes blood flow abnormalities.

Inherit Mode: The mode of inheritance is not known for atrial septal defects, but many congenital cardiac defects are believed to have a polygenic mode of inheritance, with variable expression. This means that many individual genetic contributors must exist to result in an atrial septal defect.

Disease Symptom: The main determinant of the impact of an atrial septal defect is its size.  A small defect usually will be of no significance to a dog, and indeed most dogs with small atrial septal defects live normal lives. With larger defects, however, there will be abnormal blood flow from the higher pressure left side of the heart across the defect to the right side. This causes more work for the heart , which can eventually lead to congestive heart failure. Signs may include respiratory difficulties, fainting, tiring with exercise, abnormal cardiac rhythms, and abdominal swelling due to fluid retention from the disrupted circulation.

Disease Cause: -

Disease Diagnose: Often, as with most heart defects, the first indication of a problem is when the veterinarian hears a heart murmur during a puppy's first physical examination for vaccinations (8-10 weeks of age). In the most serious cases, with very large atrial septal defects, there may be visible symptoms, such as exercise intolerance or respiratory difficulties, that prompt a visit to the veterinarian, where an atrial septal defect is discovered. A heart murmur alone is never conclusive for atrial septal defects, because many other cardiac defects cause similar murmurs, and many pups may have healthy hearts and a murmur that goes away after a few weeks as part of normal growth. Therefore, if the features of a heart murmur make the veterinarian suspicious of the possibility of an atrial septal defect, then he or she will recommend tests, especially thoracic radiographs (chest X-rays) and an echocardiogram (also called cardiac ultrasound or sonogram of the heart). These noninvasive tests can identify clearly whether an atrial septal defect is present, and if it is, whether there is reason for concern (and whether treatment is necessary).

Treat Method: In humans, surgical closure of an atrial septal defect is commonplace, and can be undertaken either with open-heart surgery or with minimally-invasive catheter-based interventions.  In dogs, such operations are challenging and rarely undertaken.  In the absence of symptoms, most dogs with atrial septal defects do not receive treatment.  Thankfully, most dogs with atrial septal defects have small defects that are of no consequence.  Dogs whose atrial septal defect is sufficiently large to cause symptoms receive oral medications at home to alleviate the symptoms rather than treating the underlying cause.

Breeder Advice: Affected individuals and their parents should not be used for breeding. Siblings should only be used after careful screening.

Disease Description Source: Link