Congenital heart disease in dogs and cats - PDA and PRAA

Congenital defects of the heart vessels occur fairly often in dogs and occasionally in cats as well. The most common defects are patent ductus arteriosus (PDA) and persistent right aortic arch (PRAA). These defects arise because certain blood vessels fail to close properly, or form abnormally, during embryonic development.

In this article we discuss the causes, symptoms, diagnosis, and treatment of PDA and PRAA in pets.

What are abnormal heart vessels?

During the development of the heart and the major blood vessels in the womb, temporary vessels are used to support the circulation. When these fail to close properly or form incorrectly after birth, we speak of congenital heart vessel defects.

Patent ductus arteriosus (PDA)

PDA is more common in dog breeds such as the Cavalier King Charles Spaniel, Miniature Poodle, German Shepherd, Labrador Retriever, and Chihuahua. It is rare in cats.

The ductus arteriosus is a blood vessel that connects the pulmonary artery to the aorta during pregnancy. Normally this vessel closes shortly after birth. When this doesn't happen, it is called a patent ductus arteriosus (PDA). With PDA, blood flows back from the aorta into the pulmonary artery, which leads to overload of the heart and lungs.

Persistent right aortic arch (PRAA)

PRAA is often seen in breeds such as the Great Dane, German Shepherd, and Irish Setter. Cats can develop this too, although it is exceptional.

With PRAA, the aorta develops abnormally on the right side instead of the left. This creates a ring-like structure that can constrict the esophagus. As a result, young animals have difficulty eating and often regurgitate food.

Symptoms

Symptoms of PDA

• A distinct heart murmur (audible to the veterinarian, not detectable by the owner).
• Your dog breathes faster or becomes out of breath after playing.
• Fatigue and reduced stamina during walks or play.
• In severe cases, signs of heart failure such as coughing, fainting, or fluid buildup.

Symptoms of PRAA

• Your puppy or kitten brings food back up shortly after eating, without retching beforehand (regurgitation).
• Difficulty swallowing or frequently stopping while eating.
• Weight loss despite a good appetite.
• Recurrent pneumonia due to aspiration.

Diagnosis and treatment of PDA and PRAA

The diagnosis is made through a combination of examinations:

• Physical examination and listening for a heart murmur (for PDA)
• X-rays of the chest and esophagus
• Echocardiography to assess blood flow and heart function
• Contrast studies or a CT scan to confirm PRAA

Treatment of PDA

A PDA can be successfully treated with surgery or a catheter-based intervention in which the vessel is closed off with a plug or coil. Early treatment is crucial to prevent heart failure.

Treatment of PRAA

For PRAA, surgery is the only effective treatment. During the operation, the abnormal vascular structure is cut to free the esophagus. Recovery afterward can vary depending on the extent of lasting damage to the esophagus.

Prognosis for PDA and PRAA

The prognosis for PDA is excellent when treated surgically at an early stage. For PRAA, the prognosis depends on how quickly the diagnosis is made and the surgery performed. Animals that have been regurgitating for a long time may have lasting esophageal problems.

Want to know more?

Read more about cardiology and congenital heart defects at Nesto. Our specialized veterinarians have extensive experience diagnosing and treating PDA and PRAA.

Frequently asked questions (FAQ)

Which breeds are more prone to PDA?

Mainly the Cavalier King Charles Spaniel, Miniature Poodle, German Shepherd, Labrador Retriever, and Chihuahua.

Which breeds more often develop PRAA?

This is most often seen in the Great Dane, German Shepherd, and Irish Setter.

What is the difference between PDA and PRAA?

PDA is an open connection between the aorta and pulmonary artery, while PRAA is an abnormal formation of the aorta that constricts the esophagus.

Are PDA and PRAA common?

PDA is more common in dogs; PRAA is seen in both dogs and cats but is rarer.

How is PDA treated?

With surgery or a catheter-based intervention in which the vessel is closed off.

What are the symptoms of PRAA?

Mainly regurgitation and difficulty eating due to constriction of the esophagus.

Is the prognosis good after treatment?

Yes, PDA has an excellent prognosis; the prognosis for PRAA depends on the extent of lasting esophageal damage.

My puppy spits up its food right after eating - what could this be?

This may indicate PRAA. In this condition, the esophagus is constricted, preventing food from passing through properly.

Why does my dog get out of breath quickly during walks?

With PDA, blood flows incorrectly through the heart, which can lead to overload of the heart and lungs. You'll notice this as fatigue and rapid breathing.

At what age will I notice signs of these defects?

Symptoms often appear already in young animals. With PRAA, this is often as soon as puppies switch to solid food; with PDA, it's often within the first few months, through fatigue and a heart murmur.