In Atrial Septal Defects (ASD), the blood tends to flow from the right atrium to the left atrium due to the relatively high pressure exerted by the blood returning to the heart from the body circulation. This phenomenon prevents blood in the heart from being pushed into the lungs leading to poor oxygenation of blood cells and consequently a decrease in the circulating oxygen in the body. Depending on the size and location of the hole in the cardiac muscle wall, minor defects may not result in any visible signs while larger defects often result in an imbalance in blood pressure within the heart.

Most Bulldogs diagnosed with the condition usually live normal lives but those with severe forms die from secondary defects of the heart.

A veterinarian can diagnose ASD in a Bulldog upon detecting a significant heart murmur while doing a thorough physical examination. Bulldogs suffering from the condition may show evidence of heart problems as shown by poor exercise tolerance and/or mucus membranes or tongue with a bluish tinge. Other signs include swelling of the abdomen, breathing difficulties, collapse or even death.

ASD may also incidentally show up on routine x-rays. Chest x-rays will demonstrate a right-side heart enlargement while an echocardiography (ultrasound of the heart) can reveal the abnormal physical changes in the dimensions of the heart and the blood flowing though from the heart to the lungs.

The treatment regimen for ASD depends on the size of the defect and the existence of other heart abnormalities. Although a Bulldog may already be diagnosed with the condition at an early age, no treatment is indicated until clinical signs are manifested. In moderate to severely affected dogs, heart medications may be given to maintain normal functioning of the heart and for the relief of respiratory congestion. Most veterinarians prescribe a special heart-friendly diet and tell the dog owner to restrict the dog’s activity.

Surgery has been done in some cases where an affected suffers from multiple heart problems but results were not as promising. Thus, most veterinarians believe that the condition is best left managed with drugs.

Since it is a hereditary condition, screening of dogs which are predisposed to the disease as well as those whose littermates have been diagnosed with the disease should be done before breeding to prevent affected animals from passing on the defect to its offspring.