Ventricular septal defect
Ventricular septal defect (VSD) is a congenital disease of dogs characterized by a hunting of blood from the left to right chambers of the heart.
This condition in dogs is relatively rare and constitutes about 7% of congenital heart diseases. Some are considered innocent in the respect of self-resolving with age, but many are large and worsen as the dog matures.
Although most VSDs are a defect with communication between left and right ventricles, abnormal VSDs can occur as left ventricular-right atrial communications, known collectively as Gerbode defects.
Clinical signs are normally seen in young dogs (1 - 2 years of age) but can present at an older age with symptoms of generalized weakness, exercise intolerance, syncope, abdominal swelling associated with ascites and pale mucus membranes. A cough may be present intermittently.
A tentative diagnosis can be established by auscultation of a holosystolic heart murmur and radiographic evidence of cardiomegaly but definitive diagnosis requires use of M-mode and Doppler echocardiography.
ECGs usually reveal varying degrees of left or right bundle branch block.
Echocardiographs usually elucidate the septal defect and often shows concurrent right ventricular hypertrophy.
A differential diagnosis would include atrial septal defect, double-chambered right ventricle, hyperthyroidism, cardiomyopathy, Duchenne muscular dystrophy, endocarditis, mitral valve endocardiosis, other causes of congestive heart failure and infections with Dirofilaria spp.
Treatment is usually conservative, with management of the secondary congestive heart failure, but surgical correction can be performed at specialty referral centers using cardiopulmonary bypass. New surgical techniques are also reported such as a pan-nitinol occluder device for transcatheter closure of the defect.
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