CONDITION
Patent Ductus Arteriosus
Patent ductus arteriosus is a condition in which a blood vessel that normally closes soon after birth remains open. Before a puppy or kitten is born, a short vessel called the ductus arteriosus connects two of the large arteries leaving the heart, allowing blood to bypass the lungs while they are not yet functioning. In most animals, this vessel closes within the first few days of life; when it does not, blood continues to flow through it in a pattern that places extra strain on the heart and lungs. Owners most commonly encounter this condition when a murmur is detected during a routine puppy or kitten check, often before any signs are apparent. In some cases, an animal may show reduced energy, slower growth, or changes in breathing pattern as the heart begins to work harder. The condition occurs more frequently in certain breeds, and the severity of signs depends largely on how much blood is moving through the open vessel. This page explores the signals that may bring this condition to attention, the mechanisms by which the open duct affects circulation and heart function, the investigations used to confirm and characterise it, and the range of approaches that exist for managing it.
Why this matters now
Patent ductus arteriosus is a condition present from birth, though the timing of detection varies. The vessel in question is meant to close within the first two to three days of life, and when it remains open the pattern becomes established in the early weeks. Certain breeds appear more frequently in clinical records, including Poodles, German Shepherds, Collies, and Maltese dogs, though the condition can occur in any breed or in cats. The signs, when they appear, often begin to surface in the first few months as the heart adjusts to the altered workload.
The course of this condition depends largely on the volume of blood moving through the open duct. In some animals, the heart compensates for a period and signs remain subtle or absent for weeks or months. Over time, the left side of the heart may begin to enlarge as it works to manage the extra circulation, and fluid can begin to accumulate in the lungs. The rate at which this progression occurs varies between individuals; some animals remain stable for extended periods, whilst others show changes more quickly.
Signals & patterns
Early signals
Murmur detected at routine check
A continuous heart murmur is often the first finding, typically noticed during a puppy or kitten vaccination appointment. The murmur may be audible in a characteristic location on the chest, and the animal may otherwise appear entirely well.
Reduced stamina during play
Some young animals tire more quickly than their littermates during energetic activity. The difference may be subtle at first, noticed as a tendency to rest whilst others continue or a reluctance to sustain vigorous play.
Slower weight gain or growth
Growth can lag behind expected rates, particularly in puppies with larger volumes of diverted blood. The animal may eat normally but fail to match the size or weight of siblings at the same age.
Occasional coughing
A soft, intermittent cough may develop as fluid begins to accumulate in the lungs or as the enlarged heart places pressure on the airways. The cough is often more noticeable after rest or in the morning.
Later signals
Increased breathing effort at rest
Breathing may become more rapid or require visible effort, particularly when the animal is lying down. The chest may appear to move more than expected, and the pattern may worsen gradually over days or weeks.
Exercise intolerance
The animal may stop during walks, choose to lie down rather than move, or show reluctance to engage in activities previously enjoyed. Recovery after exertion may take longer than it once did.
Changes in gum colour or capillary refill
The gums may take on a slightly dusky or pale tone, and the time taken for colour to return after gentle pressure may lengthen. These changes reflect alterations in circulation and oxygen delivery.
Click to read about the biological mechanisms
How this is usually investigated
Options & trade-offs
Last reviewed: Invalid Date ·