Small Animal Radiology and Ultrasound: A Diagnostic Atlas and Text

Chapter Two The Thorax 149
Fig. 2-124 A and B, A 6-month-old
male Scottish Terrier with a grade
5/6 systolic murmur. The dog had
exercise intolerance and was cyanotic.
The cardiac silhouette shows
slight right-sided enlargement. The
pulmonary vessels appear smaller
than normal. No other abnormalities
are noted. The radiographic findings
are indicative of congenital heart disease,
most likely tetralogy of Fallot.
Diagnosis: Tetralogy of Fallot.
A
B
Radiographic abnormalities are uncommon. The cardiac silhouette is usually within
normal limits. The main pulmonary artery may appear normal or may be mildly dilated.
Smaller pulmonary arteries usually will appear hypoperfused.
Echocardiography is usually diagnostic in these cases due to the right ventricular
hypertrophy in response to the pulmonary arterial hypertension. The lesions associated