Congenital Heart Defect (Pulmonic Stenosis) in Dogs

Pulmonic Stenosis in Dogs

Pulmonic stenosis is a congenital (present at birth) defect characterized by the narrowing and obstruction of blood through the heart’s pulmonary valve, which connects the pulmonary artery to the right ventricle (one of the heart’s four chambers). Depending on the severity of the obstruction, it can cause anything from a murmur to an arrhythmia to congestive heart failure.

The breeds most susceptible to this defect include the English bulldog, Scottish terrier, wirehaired fox terrier, miniature schnauzer, West Highland white terrier, Chihuahua, Samoyed, mastiff, cocker spaniel, boxer, and beagle.

Symptoms and Types

There are three types of pulmonic stenosis: valvular pulmonic stenosis (occurring in the valve), subvalvular pulmonic stenosis (occurring below the valve, and supravalvular pulmonic stenosis (just inside the pulmonary artery). Valvular pulmonic stenosis is the most common form seen in dogs.

If the stenosis is mild, no clinical symptoms may be present, whereas severely affected patients may collapse with exertion or suffer from congestive heart failure (CHF). Other visible signs of pulmonic stenosis include:

• Abdominal distention
• Difficulty breathing
• Inability to exercise normally

Causes

Congenital (present at birth).

Diagnosis

You will need to give a thorough history of your dog’s health, including the onset and nature of the symptoms, to your veterinarian. He or she will then perform a complete physical examination, as well a biochemistry profile, urinalysis, and complete blood count (CBC) — the results of which are typically normal. Some dogs may also be revealed to have polycthemia, a condition which causes an abnormally high number of red blood cells.

Other diagnositc procedures include thoracic X-rays (which may show heart enlargement), abdominal X-rays (which may show abnormal accumulation fluid in abdominal cavity (ascites), and echocardiography (which may show increase in size of right ventricle and other abnormalities related to ventricle). A more advanced version of echocardiography, Doppler Echocardiography, may be used to measure the speed of blood flow. Angiography, on the other hand, is an imaging technique used to visualize the inside of blood vessels and heart chambers, which can help identify the precise structural abnormalities before surgery.