Feline patent ductus arteriosus

Patent ductus arteriosus (PDA), although not as common in the cat as in the dog, is important because it is one of the few cardiovascular anomalies that can be corrected surgically. The ductus arteriosus is a blood vessel that connects the two main arteries of the body - the aorta and the pulmonary artery. This blood vessel is normal in the fetus, but shortly after birth, it should close. When the ductus arteriosus remains open or patent after birth, this abnormal communication between the aorta and pulmonary artery passes extra volumes of blood into the lungs.

Patent ductus arteriosis (PDA) is a birth defect representing the second most common congenital heart defect of cats. Approximately seven out of 1000 live birth kittens are affected. Generally, there are no serious symptoms of PDA unless congestive heart failure has caused fluid buildup in the lungs. The condition is typically identified in kittens during a routine veterinary visit for vaccinations. Continual blood flow through the PDA into the lungs produces a continuous (machinery) heart murmur.

Even when the veterinarian identifies a PDA, most people believe their cat is normal. In some cases, the cat can be smaller than littermates or play less vigorously. However, the situation can be very misleading as symptoms usually occur within a year of diagnosis. If untreated, about 60 percent of affected cats die within a year of diagnosis.

When caught early, and following treatment with successful closure of the PDA, most cats live a normal life. Unless there are complications from other heart defects or heart failure has already developed, there is rarely any future need for medication. While special circumstances can influence the prognosis, most cases are straightforward.

Patent ductus arteriosus is genetically determined in almost every case, and this fact impacts the value of purebred cats used for breeding.