Interruption of aortic arch in two foals.

This research investigates two foals (baby horses) who started their life in good health but soon started showing signs of exercise intolerance and weakness. Further medical examinations identified cardiovascular defects. Post-mortem analysis revealed a number of heart defects, including the congenital absence of the aortic arch.

Initial Signs and Physical Examination

• The two foals examined in this study were originally observed to be healthy at birth. However, they began to exhibit signs of poor exercise tolerance and general weakness within the first few days of life. These symptoms are usually indicative of some form of health distress in young animals.
• Common complaints from the foals were weakness, an inability to rise, and a noticeable reluctance to suckle. These symptoms further suggested that the foals were suffering from a physical ailment.
• Upon physical examination, a cardiovascular abnormality was discovered in both foals. There was a loud systolic murmur, a type of heart murmur that occurs during a heartbeat’s contraction, that could be heard over both thoracic walls. This is a clear symptom of a problem with the heart.

Diagnostic Techniques and Findings

• Beyond the physical examination, the research employed other diagnostic techniques to determine the cause of the foals’ condition. These included blood gas analysis, which measures the amount of oxygen and carbon dioxide in the blood, radiography for creating image profiles, cardiovascular catheterization, a method to examine how well the heart is working, and necropsy, which is an autopsy performed on animals.
• The post-mortem necropsy findings revealed several serious heart conditions in the foals. These included a ventricular septal defect, a condition characterized by a hole in the wall separating the heart’s lower chambers, an atrial septal defect, which is a hole in the wall between the heart’s upper chambers, and patent ductus arteriosus, a persistent, abnormal blood vessel connection.
• The most noteworthy discovery was the congenital absence of the aortic arch, meaning that the main artery normally carrying oxygenated blood from the heart to the rest of the body was missing.
• One of the foals also had an additional defect: an anomalous drainage of the cranial vena cava into the left atrium. In a normal heart, the cranial vena cava, a large vein, carries deoxygenated blood to the heart’s right atrium. However, in this case, it was leading into the left atrium, which typically receives oxygen-rich blood from the lungs.