Persistent Fetal Heart Vessel in Dogs (Patent Ductus Arteriosus, PDA)
- Synonyms: Ductus arteriosus Botalli, DAB, Ductus aorticus
- Occurrence: very rare
- Location of disease: Chest
When to visit the vet?
Urgent see a veterinarian within 24 hours
If the condition worsens / symptoms persist, consult a veterinarian.
Definition
Patent ductus arteriosus (PDA) is a congenital heart defect in dogs in which the ductus arteriosus, a blood vessel that normally closes at birth, remains open, leading to abnormal blood flow circulation between the aorta and the pulmonary artery.
The most important facts at a glance
Patent ductus arteriosus (PDA) is a heart condition in dogs where a major blood vessel that should close after birth remains open. During fetal development, the ductus arteriosus bypasses the lungs as the fetus receives oxygen via the placenta. After birth, the lungs should expand and this vessel should close. In dogs with PDA, however, it remains open, leading to mixed blood flow and an overload of the heart. In the long term, this can lead to heart failure. The exact cause is unclear, but genetics are significant, and certain breeds such as Poodles and German Shepherds are more commonly affected. Symptoms range from heart murmurs and reduced exercise tolerance to Respiratory distress. For diagnosis, the veterinarian uses clinical examinations, echocardiography, and X-rays. Treatment is usually surgical by closing the vessel, which significantly improves the prognosis. Medications may be used temporarily to relieve symptoms. Early diagnosis and treatment are crucial for the prognosis. Prevention focuses on responsible breeding practices and avoiding risk factors during pregnancy. Regular follow-up examinations ensure the heart health of operated dogs. A balanced diet for the pregnant bitch can reduce the risk of heart defects.
Causes
The ductus arteriosus is an important blood vessel in the fetus that bypasses the lungs because the unborn animal’s oxygen needs are met via the placenta. After birth, when the lungs take over oxygenation, this vessel should close. Closure is triggered by the rise in blood oxygen levels and the drop in prostaglandins, natural chemical messengers.
In dogs with PDA, however, this channel remains open, leading to a mixture of oxygen-rich and oxygen-poor blood. This overloads the heart, especially the left atrium and left ventricle, as they have to pump more blood than usual. In the long term, this can lead to heart failure.
The exact cause of a patent ductus arteriosus is not fully understood, but genetic factors play a major role. Certain dog breeds, such as Poodles, German Shepherds, and Cavalier King Charles Spaniels, have a higher predisposition, suggesting a hereditary component. Environmental factors during pregnancy, such as infections or malnutrition, may also increase the risk.
Symptoms
Dogs with a patent ductus arteriosus can have a variety of symptoms, depending on the size of the defect and the amount of blood being shunted. In many cases, symptoms are visible in the first weeks or months of life.
The most common signs include reduced exercise tolerance, rapid breathing, Cough, and delayed growth. During the physical examination, a characteristic heart murmur, known as a “machinery murmur,” can be heard, caused by turbulent blood flow in the patent ductus arteriosus.
In severe cases, dogs may also show signs of heart failure, such as Respiratory distress, abdominal dropsy, or fainting spells. Untreated, the condition can ultimately lead to heart enlargement and life-threatening complications.
Therapy
In most cases, treatment of patent ductus arteriosus in dogs is surgical. The procedure involves tying off or closing the open vessel to stop the abnormal blood flow. This can be done either through traditional surgery or via a minimally invasive catheter-based procedure.
Surgical closure has a high success rate and can significantly improve the affected dog’s prognosis. The choice of approach depends on several factors, including the dog’s size, age, severity of the defect, and the surgeon’s experience.
In some cases—especially when surgery is not immediately possible—medications may be used to control symptoms and support heart function. These may include diuretics, an ACE inhibitor, and cardiac glycosides to help reduce the strain on the heart.
Prognosis and follow-up care
The prognosis for dogs with patent ductus arteriosus depends heavily on timely diagnosis and treatment. With early detection and successful surgical correction, many dogs can live a normal, healthy life.
Untreated, the course is often unfavorable, as the continuous strain on the heart can lead to progressive heart failure and ultimately to Death. Therefore, it is crucial to recognize and treat the defect as early as possible.
Dogs that undergo successful surgery usually have a very good quality of life, and many experience no further heart problems. However, regular follow-up examinations are important to monitor heart health.
Prevention
Because patent ductus arteriosus is often genetic, prevention focuses primarily on avoiding breeding affected animals. It is important to educate breeders and owners about the risks and the genetic component, especially in predisposed breeds.
Screenings and genetic tests can help identify carriers and affected dogs to prevent passing the defect on to future generations. Responsible breeding practices can help reduce the incidence of this malformation in the dog population.
In addition, avoiding risk factors during pregnancy—such as stress, infections, and malnutrition—can help reduce the risk of congenital heart defects. A balanced, nutrient-rich diet for the pregnant bitch can support healthy fetal development.
Outlook on current research
Research into patent ductus arteriosus (PDA) in dogs aims at earlier detection, more tailored planning, and even gentler procedures. For early detection, AI-supported analyses of heart murmur recordings and simplified echocardiography screening protocols for breeding lines are being evaluated to identify at-risk litters early. In procedure planning, 3D imaging, CT angiography, and patient-specific 3D models are becoming more important: they help measure the ductus’ size and shape more precisely and select the right occlusion design to avoid residual shunts. In parallel, industry is improving catheters and products for very small patients; at the same time, low-cost alternatives are being tested for regions with limited resources.
Another focus is PDA-associated pulmonary hypertension (increase in blood pressure and vascular resistance in the pulmonary circulation): studies are investigating reversibility testing as well as agents for vasodilation (widening of blood vessels), e.g., phosphodiesterase-5 inhibitors, and defining clear thresholds for when closure is safe. Registry and multicenter projects aim to systematically capture long-term outcomes, arrhythmia, recurrence / relapse, and quality of life, thereby standardizing follow-up intervals. Genetic work is still in its early stages but could support breeding advice and risk assessment in the future. The overarching goal remains: to close PDA earlier, more safely, and more individually—with short hospital stays, reliable regression of heart enlargement, and consistently excellent exercise tolerance.
Frequently Asked Questions (FAQs)
1. What is a PDA?
2. How do I recognize it?
3. How is the diagnosis made?
4. Does every PDA need to be treated?
5. How is it treated?
6. When is the best time?
7. What are the chances of success and quality of life?
8. Are there any risks or complications?
9. Does my dog need medication?
10. What is important after the procedure?
Literature
- Saunders, A. B., Gordon, S. G., Boggess, M. M., & Miller, M. W. (2014). Long-term outcome in dogs with patent ductus arteriosus: 520 cases (1994–2009). Journal of Veterinary Internal Medicine, 28(2), 401–410. https://doi.org/10.1111/jvim.12267
- Ciccozzi, M., Stauthammer, C. D., Coats, C., Oberholtzer, S., Masters, A., Gavic, E., Rendahl, A., & Tobias, A. (2025). Transcatheter Amplatz canine duct occluder placement for patent ductus arteriosus occlusion: A retrospective analysis of outcomes and complications in 200 dogs. Journal of Veterinary Cardiology, 60, 36–45. https://doi.org/10.1016/j.jvc.2025.05.002
- Markovic, L. E., Hiremath, G., Scansen, B. A., Kellihan, H. B., Calkins, C., Coleman, A. E., Tjostheim, S. S., Tainter, B., Hodges, K. M., Cahill, E., Carter, M., & Kim, D. W. (2024). Comparative transcatheter occlusion of patent ductus arteriosus: Multicenter collaborative study across pediatric and veterinary cardiology centers. Journal of Veterinary Cardiology, 56, 72–83. https://doi.org/10.1016/j.jvc.2024.08.008
- Singh, M. K., Kittleson, M. D., Kass, P. H., & Griffiths, L. G. (2012). Occlusion devices and approaches in canine patent ductus arteriosus: Comparison of outcomes. Journal of Veterinary Internal Medicine, 26(1), 85–92. https://doi.org/10.1111/j.1939-1676.2011.00859.x
- Gordon, S. G., Saunders, A. B., Achen, S. E., Roland, R. M., Drourr, L. T., Hariu, C., & Miller, M. W. (2010). Transarterial ductal occlusion using the Amplatz Canine Duct Occluder in 40 dogs. Journal of Veterinary Cardiology, 12(2), 85–92. https://doi.org/10.1016/j.jvc.2010.04.004
- Nguyenba, T. P., & Tobias, A. H. (2007). The Amplatz canine duct occluder: A novel device for patent ductus arteriosus occlusion. Journal of Veterinary Cardiology, 9(2), 109–117. https://doi.org/10.1016/j.jvc.2007.09.002
- Campbell, F. E., Thomas, W. P., Miller, S. J., Berger, D., & Kittleson, M. D. (2006). Immediate and late outcomes of transarterial coil occlusion of patent ductus arteriosus in dogs. Journal of Veterinary Internal Medicine, 20(1), 83–96. https://doi.org/10.1111/j.1939-1676.2006.tb02827.x