4. Diseases of the thoracic cavity in dogs and cats (hydrothorax, pneumothorax, diaphragmatic hernia). Differential diagnosis of pleural fluid accumulation. Flashcards
Hydrothorax?
Hydrothorax
Type of pleural effusion whereby transudate accumulates in the
pleural cavity
Disease that is often secondary to CHF (mainly in cats)
Also caused by:
§ Hypoalbuminaemia
§ Diaphragmatic hernia
§ Portal hypertension
Pneumothorax?
Pneumothorax
Air accumulation in the pleural space (pneumomediastinum)
Classification
§ Traumatic: Trauma; Penetrating injury
§ Spontaneous: Idiopathic; Secondary (by airway rupture);
Simple/complicated/tension; Open/closed
CSx: Inspiratory dyspnoea; ↓ Lung & heart sounds; ↓ Respiratory
sounds; ↑ Resonance; Underlying trauma; Cyanosis
Dx: Physical exam; Thoracocentesis/Radiography
Radiological features (See Fig. 4.1)
§ Elevation of the heart from the sternum
§ Demarcation of intrathoracic organs
§ Lung lobe compression
§ ↑ Density of the pulmonary parenchymal tissue
§ Free air between visceral & parietal pleura
§ Ø Pulmonary vascular structures in the periphery
Tx: Thoracocentesis/chest tubing; Blood-patch pleurodesis; Oxygen
therapy; Surgery; Control radiography
If complicated case: Insert a thoracic drainage catheter
Diaphragmatic hernia?
Diaphragmatic Hernia
Abdominal contents enter the thoracic cavity
Classification
§ Pleuroperitoneal/peritopericardial (PPDH)
§ Traumatic > Congenital (PPDH > Hiatal hernia)
CSx: Mixed/inspiratory dyspnoea; Shock; Stomach distension;
Dullness; Asymmetric respiratory noises; Shock; Cyanosis;
Arrhythmia
Dx: Physical exam; Radiography; Ultrasonography
Beware that performing a thoracocentesis may produce blood-tinged
fluid
Tx: Surgery
Differential diagnosis of pleural fluid accumulation?
Differential Diagnosis of Pleural Fluid Accumulation
Pleural fluid accumulation = Pleural effusion
A build-up of excess fluid between the layers of the pleura outside the lungs
Usually caused by multiple factors
Fluid originating from pulmonary capillaries
§ ↓ Plasma oncotic pressure (hypoproteinaemia)
§ ↓ Pleural pressure (atelectasis)
Fluid originating from systemic capillaries
§ ↑ Vascular permeability (inflammation)
§ ↑ Venous pressure (heart failure)
Fluid originating from the abdomen: Through diaphragmatic holes
Cardiac disease Lung lobe torsion
Diaphragmatic hernia Pancreatitis
FIP Pericardial disease
Heartworm Neoplasia
Idiopathic Venous thrombi
Fluid originating from the lymphatic vessels
§ Blockage of lymphatic stoma
§ Compression due to obstruction
§ ↓ Flow due to ↑ venous pressure
§ Injury from chemotherapy/radiation
§ Limitation of respiratory motion
Causes of build-up: ↑ fluid formation or ↓ fluid drainage
Primary causes of pleural effusion
CSx: Inspiratory dyspnoea; Delayed expiration; Extended neck;
Tachypnoea; Open mouth breathing; Cyanosis
Physical exam
§ Percussion: Horizontal dullness; Diernhofer triangle “air-containing angle” disappears
§ Auscultation: Bronchial sounds above fluid; Ø sounds
under the fluid
Dx
§ Radiography: Blunting on costophrenic & cardiophrenic
angles ; Meniscus signs
§ Ultrasonography: Gold standard for dx
§ Lab. D: CBC; Electrolytes; Urea; LFT-protein
§ Thoracocentesis → Transudate; Modified transudate;
Exudate
Types of pleural effusion?
TYPES OF PLEURAL EFFUSION
§ Hydrothorax (see earlier)
§ Pyothorax
§ Chylothorax
§ Haemothorax
Pyothorax, Chylothorax and
PYOTHORAX
Septic exudate/pus in the pleural cavity
Causes
§ Infection: Severe bacterial infection in the chest cavity;
Blood-borne infection/Penetrating chest wound
§ Obligate anaerobe infection – Mainly via skin injury
§ Migratory foreign material
Other causes
CHYLOTHORAX
Lymph in the pleural cavity
Opaque to pink exudate upon thoracocentesis
Causes
§ ↓ Lymphatic drainage
§ Idiopathic
§ Congenital (weakness of the lymphatic vessels –
Lymphangiectasia)
§ Non-traumatic: RS-HF; Compression of thoracic duct (by
a tumour/inflammatory adhesion)
§ Traumatic: Rupture of thoracic duct
Dx:
§ Thoracocentesis → Cytology;
§ Triglycerides: Pleural fluid > Blood plasma
§ Lymphangiography
Tx: Thoracocentesis; Treat underlying disease; Low-fat diet;
Surgery; Low fat diet
HAEMOTHORAX
Blood in the pleural cavity
Causes
§ Trauma § Ruptured granuloma
§ Neoplasia § Thymus apoplexy (dog)
§ Coagulopathies
Tx: Chest drain; Treat underlying disease; Thoracic lavage; Surgery
