SAEVA Congress 2018 Proceedings | 12-15 February 2018 | ATKV Goudini Spa
Spleen in the left thorax in a horse with a diaphragmatic hernia
Patient Management and Prognosis
The thoracic ultrasound examination can be used to help form a more accurate
prognosis for survival and select appropriate treatment at the horse's initial
presentation, as well as monitoring response to therapy. The findings on sonographic
examination can be used to decide if thoracocentesis is indicated and to select the
most productive site for thoracocentesis. The thoracic ultrasonographic examination
can also be used to determine when antimicrobial therapy can be discontinued, to
monitor the horse thereafter.
Survival of horses with pleuropneumonia is more likely if pleural fluid, fibrin, loculations,
free gas echoes, or parenchymal necrosis are not detected on the initial
ultrasonographic examination.
Survival rates of horses with anaerobic
pleuropneumonia vary from 32-41%, with few horses successfully returning to their
prior performance level. If free gas echoes are detected in pleural fluid, a guarded to
grave prognosis should be given and broad spectrum antimicrobial therapy, including
coverage effective against anaerobic microorganisms (metronidazole), initiated
immediately before results of culture and sensitivity testing are available. The detection
of parenchymal necrosis also warrants a grave to guarded prognosis initially, as only
30% of horses with parenchymal necrosis survived in one study. Also, 50% of horses
with parenchymal necrosis had free gas echoes detected in their pleural fluid
(anaerobic pleuropneumonia), and 30% had pulmonary abscesses. Horses with
parenchymal necrosis should also be treated aggressively with broad-spectrum
antimicrobials, including covering the anaerobic spectrum. If pulmonary infarction or
thromboembolism is suspected, the affected area of the lung should be examined with
color flow and power Doppler ultrasonography to determine if there is normal
pulmonary blood flow to the affected portion of the lung. The ultrasonographic
detection of fibrinous pleuropneumonia, with or without loculations, warrants a guarded
prognosis initially and the initiation of broad-spectrum antimicrobial therapy, after
obtaining a transtracheal fluid aspirate and pleural fluid aspirate for culture and
sensitivity testing. The survival of horses with fibrinous pleuropneumonia and loculated
fibrinous pleuropneumonia is 52% and 40% respectively, with a better chance of
affected horses returning to their prior performance level.
The cost effectiveness of treatment must be considered because horses with anaerobic
pleuropneumonia or parenchymal necrosis are likely to require a longer period of
antimicrobial treatment and are unlikely to return to their prior performance level, if they
survive. The number of treatment days was longer for horses with pleuropneumonia
when pleural fluid, fibrin, loculations, free gas echoes, pulmonary parenchymal
necrosis, or abscesses were detected ultrasonographically at initial examination.
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