SAEVA Congress 2018 Proceedings | 12-15 February 2018 | ATKV Goudini Spa
Fibrinous anaerobic pleuropneumonia
Fibrin has a filmy to filamentous or frond-like appearance and is usually hypoechoic.
Fibrin is deposited in layers or in web-like filamentous strands on the parietal and
visceral pleural surfaces. Fibrin was detected ultrasonographically in 23% of horses
with pleuropneumonia. Loculations between the parietal and visceral pleural surfaces
of the lung, diaphragm, pericardium, and inner thoracic wall limit pleural fluid drainage.
Loculations were detected ultrasonographically in 10% of horses with pleuropneumonia
and in 56.5% of horses with fibrinous pleuropneumonia. As these fibrin strands
become more organized and fibrous they become more rigid and echogenic, often
distorting the structures to which they are attached during one phase of respiration and
possibly restricting pulmonary mechanics. This fibrin may eventually organize in the
cranial mediastinum and wall this area off from the rest of the thorax, resulting in a
cranial mediastinal abscess.
Pneumothorax
A gas-fluid interface is detected in horses with hydropneumothorax (pleural effusion
and pneumothorax). This pneumothorax i s usually caused by a bronchial-pleural
fistula that occurs in horses with severe pulmonary parenchymal necrosis. The gas
fluid interface can be imaged moving simultaneously in a dorsal to ventral direction with
respiration, the "curtain sign", reproducing the movements of the diaphragm. The
curtain sign is best visualized with pleural effusion, parenchymal consolidation or
atelectasis. The lung echo changes position relative to the pleural fluid, while the
dorsal free gas echo moves with pleural fluid movement and respiration. The lung is
imaged floating in the pleural fluid retracted towards the pulmonary hilus. Without
looking deep into the thorax, the underlying consolidated or atelectic lung could be
missed and the dorsal pneumothorax might be mistaken for lung.
With
hydropneumothorax the lung is not imaged adjacent to the parietal pleura because it is
surrounded by fluid and gas.
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