ภาวะหลอดเลือดหัวใจเกินในสุนัข (Patent ductus arteriosus, PDA)

Patent Ductus Arteriosus (PDA) in Dogs
By Dr. Jirasin Jintanaphusit (Dr. JJ), Khwankham Animal Hospital

Heart disease is commonly understood to be a condition that arises from degeneration and is often associated with older animals. However, in reality, heart disease can also occur in younger animals, and it is usually caused by congenital defects—those that arise due to incomplete development during gestation. These defects often lead to clinical signs during the animal’s growing phase.

Patent ductus arteriosus (PDA) in dogs is a congenital heart condition that is one of the most common heart defects seen in dogs. It occurs when the ductus arteriosus, a blood vessel connecting the aorta and the pulmonary artery, fails to close after birth. Normally, this blood vessel serves to allow blood to bypass the lungs during fetal development, as the lungs are not yet functional. After birth, once the animal begins breathing, the ductus arteriosus should close, allowing blood to flow through the lungs for oxygenation before being pumped to the rest of the body. If the ductus arteriosus remains open (patent) after birth, it causes abnormal blood flow, leading to heart failure over time.

Dogs with PDA may show symptoms from as young as a few months old to when they reach sexual maturity. The severity of the symptoms depends on the size of the remaining ductus arteriosus. Symptoms commonly observed include slow growth, easy fatigue during exercise, weakness, and if heart failure is present, signs such as coughing, difficulty breathing, and fainting may occur.

Diagnosis can often be made through physical examination, where a continuous murmur in the heart is heard, which is characteristic of this condition. In many cases, PDA is discovered incidentally during routine check-ups or vaccination appointments, even before the puppy shows any clinical signs. Chest X-rays can help assess heart enlargement and pulmonary edema, which indicate the presence of heart failure. Additionally, echocardiography (ultrasound of the heart) is an excellent tool for confirming the diagnosis and measuring the size of the remaining ductus arteriosus. If arrhythmias are present, an electrocardiogram (ECG) may also be recommended.

Medical treatment is aimed at managing heart failure symptoms and providing palliative care. The most effective treatment, however, is surgical intervention to close the ductus arteriosus and restore normal blood circulation. This can be achieved through ligation of the ductus or, in some cases, using a device to occlude the vessel. After surgery, most dogs can live normal lives without the need for ongoing medication, although long-term monitoring is necessary. Some dogs may experience heart muscle deterioration due to previous heart failure, which could lead to additional heart issues over time.