Small Animal Radiology and Ultrasound: A Diagnostic Atlas and Text

Chapter Two The Thorax 59
Fig. 2-31 A left parasternal longaxis
four-chamber (inflow) view
reveals left ventricle (lv), left atrium
(la), atrial septum (as), right atrium
(ra), and right ventricle (rv).
Diagnosis: Normal heart.
Fig. 2-32 A left parasternal long-axis five-chamber
(left ventricular outflow) view reveals the left
ventricle (lv), left atrium (la), aorta (ao), right
atrium (ra), and right ventricle (rv). Diagnosis:
Normal heart.
view is preferable. 25,67 The sample volume is placed in the middle of the aorta at the distal
end of the aortic bulb. Normal studies reveal a rapid laminar acceleration phase
(downstroke) followed by the deceleration phase (upstroke) (Fig. 2-37). A second, much
smaller wave may be seen immediately after the dominant signal, which represents early
diastolic flow. 25,67
C AU DA L V E N A C AVA
The caudal vena cava may be traced from the diaphragm to the point where it enters the
right atrium cranial to the caudal margin of the cardiac silhouette. On the lateral radiograph,
the caudal vena cava, located at about the midpoint of the thoracic height, tapers
and slopes slightly downward from the diaphragm to the cardiac silhouette. The size of the
caudal vena cava changes with respiration and phase of the cardiac cycle. It is wider and