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Pleural Effusion 791

Pleural Effusion Client Education
Sheet
VetBooks.ir Diseases and Disorders
PHYSICAL EXAM FINDINGS
BASIC INFORMATION
General: DIAGNOSIS
Definition • Dyspnea: wide chest excursions, abducted Diagnostic Overview
Accumulation of fluid within the pleural space elbows when standing, extension of Pleural effusion can be suggested by physical
is relatively common. the neck, orthopnea, anxiousness, flared exam and confirmed with thoracic radiographs,
nostrils thoracic ultrasound, or thoracocentesis. Tho-
Synonyms ○ Affected animals may have a prolonged racocentesis and fluid analysis provide precise
• General: pleural fluid, thoracic effusion inspiratory and short expiratory phase information on the nature of the fluid and
• Specific: hydrothorax (pure or modified (inspiratory effort) or dyssynchrony perhaps the underlying cause.
transudate), hemothorax, chylothorax, between the thoracic cage and abdomen
pyothorax, neoplastic exudate (paradoxical breathing; very common in Differential Diagnosis
• Chylothorax, hemothorax, and pyothorax cats) • Other pleural space disease
are discussed elsewhere on pp. 172, 436, • Muffled heart and lung sounds ventrally ○ Masses
and 857, respectively. • Normal to increased bronchovesicular lung ○ Pneumothorax
sounds dorsally ○ Constrictive/fibrosing pleuritis: can
Epidemiology • Ventral hyporesonance with thoracic percus- occur concurrently with pleural effusion
SPECIES, AGE, SEX sion; fluid line may be detected (chylothorax or pyothorax) and causes
Dogs and cats of either sex; age at presentation • Other signs associated with specific underly- rounded lung lobe contours that may be
varies with underlying cause ing cause (e.g., pallor, fever, abdominal fluid difficult to distinguish radiographically
wave, jugular pulse, heart murmur) from pleural effusion
GENETICS, BREED PREDISPOSITION • Pulmonary parenchymal/airway disease
Breed predispositions depend on underlying Etiology and Pathophysiology • Thoracic wall defects
cause (e.g., lung lobe torsion [LLT] in pugs Respiratory dysfunction reflects hypoventila- • Diaphragmatic hernia, including peritoneal/
and Afghan hounds; heart failure Maine tion and ventilation/perfusion mismatch. pericardial hernia
coon cat) Pathophysiologic mechanisms determine fluid • Neuromuscular disease
classification:
RISK FACTORS • Reduced plasma colloid oncotic pressure Initial Database
• Heart disease (cats > dogs) (hydrothorax: pure transudate) Thoracocentesis (p. 1164)
○ Pleural effusion may be seen with ○ Hypoalbuminemia: protein-losing • Diagnostic/therapeutic
right- and left-sided congestive heart nephropathy (e.g., glomerulonephritis, ○ With severe dyspnea, consider thoraco-
failure (CHF) in cats, but only right- amyloidosis); protein-losing enteropathy centesis before thoracic radiographs.
sided failure is likely to cause effusion (e.g., inflammatory bowel disease, lym- ○ Thoracic ultrasonography can also dem-
in dogs phangiectasia, neoplasia); protein-losing onstrate effusion.
• Hypoalbuminemia dermatopathy (e.g., burns, exudative skin • Thoracocentesis first
• Neoplasia disease (uncommon); vasculitis (infectious ○ Therapeutic value: removal of effusion,
• LLT or noninfectious, modified transudate improved oxygenation for patient
• Vasculitis more common); synthetic failure (e.g., ○ Diagnostic value: fluid analysis, improved
chronic hepatopathy, portal vascular radiographic visualization of parenchymal
CONTAGION AND ZOONOSIS anomalies) (p. 1239) structures: mediastinal masses, consoli-
Based on specific underlying cause (e.g., feline • Increased capillary hydrostatic pressure dated lung lobes, pulmonary masses, and
infectious peritonitis [FIP]) (hydrothorax: modified transudate) abdominal organs in the thoracic cavity
○ CHF; Budd-Chiari–like syndromes; (hernia)
Clinical Presentation thoracic or mediastinal neoplasia (also ○ Use caution if other clinical signs of
DISEASE FORMS/SUBTYPES exudate); LLT (cause vs. effect of coagulopathy found on physical exam.
Classified by fluid type (p. 1343): LLT and pleural effusions is unclear; • Radiographs first
• Hydrothorax (i.e., transudate) torsion may cause effusion, but effu- ○ Diagnostic value: confirms effusion;
• Hemothorax (p. 436) sion can also predispose to torsion); identify displacement of cardiac silhouette
• Chylothorax (p. 172) caval syndrome; heartworm disease (avoid during thoracocentesis).
• Pyothorax (p. 857) (HWD) ○ Care with positioning not to cause excess
• Reduced lymphatic drainage/lymphatic stress
HISTORY, CHIEF COMPLAINT obstruction: hydrothorax (modified tran- • Ultrasound first
• Severity of clinical signs varies with underly- sudate), chylothorax ○ Diagnostic value: confirm effusion, guide
ing cause, volume of effusion, and rate of • Pyothorax: modified transudate to exudate thoracocentesis, estimate volume of effu-
fluid accumulation. • Thoracic or pulmonary neoplasia: chylotho- sion (see above)
○ If rate is slow, large volumes may be rax, pyothorax, neoplastic exudate Diagnostics: fluid in EDTA (lavender-top) and
present before clinical signs are apparent • Increased vascular permeability (exudate) plain (red-top) tubes for analysis: total nucleated
(especially cats). ○ Pyothorax, FIP, systemic disease (e.g., and red cell counts, total protein, and cytology;
• Dyspnea, tachypnea, orthopnea pancreatitis, vasculitis) prepare fresh smears (p. 1343)
• Lethargy, exercise intolerance • Disruption of vascular integrity/hemostatic • Send fresh smears with fluid for outside
• Chronic cough (uncommon) abnormalities (hemothorax) analysis; prevents cellular degradation during
• Signs related to underlying disease (e.g., ○ Rupture of neoplastic mass, coagulopathy, shipping
pallor, weight loss, abdominal effusion, trauma, LLT, and infection (abscess, • Pyothorax culture and susceptibility (C&S):
diarrhea, signs of trauma) granuloma) aerobic and anaerobic in all cases

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