Congenital Heart Disease in Dogs
All forms of congenital heart disease occur
in dogs. The most common defects
are valve malformations (called dysplasias),valve narrowing (stenosis),abnormal
openings between the heart chambers (septal defects), patent ductus arteriosus,
and Tetralogy of Fallot.
Patent ductus arteriosusis a persistent arterial connection between the
aorta and pulmonary artery that normally closes at birth or shortly thereafter.
In the uterus, the ductus plays an important role in shunting blood away from
the nonfunctioning lungs. Many large and small breeds are affected by patent
ductus arteriosus. This murmur can often be felt through the body wall-it feels
like a washing machine churning.
Tetralogy of Fallotis a congenital defect of the heart consisting of four
abnormalities that result in insufficiently oxygenated blood pumped to the
Most dogs with severe congenital heart defects die within the first year of
life. Dogs with moderate defects may survive but usually exhibit exercise
intolerance, fainting episodes, and stunted growth. In these individuals, heart
failure can occur suddenly and unexpectedly. Dogs with mild valvular disease or
small septal defects are often asymptomatic; the only indication of a
congenital heart defect is a heart murmur discovered on physical
The diagnosis of congenital heart defect is based on ECG, chest X-rays and
echocardiogram. An ultrasound study called Doppler echocardiography measures
the velocity and direction of blood flow in the heart chambers. This
information makes the diagnosis of congenital heart defects extremely accurate.
You may need to be referred to a specialty clinic for this test.
Cardiac catheterization with angiocardiography was once the “gold standard”
for diagnosing congenital heart defects, but it carries a small risk and is
often available only at referral veterinary hospitals. Doppler
echocardiography, being accurate and noninvasive, has largely replaced cardiac
catheterization for routine diagnosis.
Treatment: Dogs with minor heart defects have a good prognosis and do not
benefit from surgery. However, many dogs benefit from surgery to correct more
severe defects. Many of these surgeries will require referral to a large
Patent ductus arteriosus is an example of a defect that does benefit from
surgery. Without surgery, 60 percent of affected puppies die within the first
year. With surgery, the death rate is less than 10 percent.
Moderate atrial and ventricular septal defects can be repaired surgically
with varying degrees of success. This requires open-heart surgery and
Valve dysplasias and large septal defects have a poor prognosis, regardless
of the method of treatment. Affected dogs are at risk of congestive heart failure and
The treatment of congestive heart failure and cardiac arrhythmias is
discussed later in this chapter.
Prevention: Most congenital heart defects have a hereditary basis. Breeds
with a known predisposition for specific congenital heart defects are shown in
the accompanying chart. This list is by no means comprehensive, and individuals
of other breeds and mixed breeds may also show these defects.