Page 30 - Feline Cardiology

Chapter 3: Pleural Effusion 21 Clinical Entities

A B

Figure 3.1. Comparison of DV (A) and VD (B) radiographic projections from 2 cats with a similar amount of pleural effusion (based on
echocardiographic examination). Note the cardiac silhouette is obliterated by the effusion in the DV view.

is severe. Ventrodorsal thoracic radiographs are superior
to the dorsoventral views for assessing heart size when
pleural effusion is present because the effusion pools
dorsally and allows better assessment of possible cardio-
megaly (Fig. 3.1). However, in many cases a dorsoventral
view to prove effusion is present prior to thoracocentesis
is justified because animals with large-volume pleural
effusion are often quite dyspneic and ventrodorsal films A
are unsafe. If life-threatening dyspnea is present, cage
rest, supplemental oxygen, ± mild sedation may be nec-
essary before the cat will allow thoracocentesis.
Butorphanol (0.2 mg/kg) with or without benzodiaze-
pine (diazepam or midazolam 0.1 mg/kg) is a commonly
used protocol. Intravenous administration is preferred
for a more rapid and predictable onset, unless restraint
for injection is likely to destabilize the patient. In some
cases it may be worthwhile to repeat radiographs after
the effusion has been removed for better assessment of
lung fields and the cardiac silhouette. Thoracic radio-
graphic findings consistent with a diagnosis of pleural
effusion vary with the amount of effusion and include
widened interlobar fissures, retraction of the pleural
surface of the lung from the thoracic wall, blunting of
the costophrenic sulci in ventrodorsal radiographs
obscuring the diaphragmatic outline, increased radioo-
pacity of the thorax, ± obliteration of the cardiac silhou- B
ette (Figure 3.2). Figure 3.2. Lateral (A) and DV (B) radiographic projections from
Echocardiography is critical to rule in, or out, heart a cat with severe pleural effusion. Note the scalloped appearance
disease as the underlying cause of effusion and can be of the lung lobes and the obliteration of the cardiac silhouette.