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The Radiographic Approach to the Coughing Dog
Matthew Cannon, DVM DACVR
Pixel Veterinary ImagingAustin, TX
Environment
• Set yourself up for success– Diagnostic quality radiographs– Visual interpretation
• Ambient lighting• Appropriate display
– Consistent approach• All structures evaluated• Systematic and repeatable process
– Organization of thoughts
Potential Sources
• Pulmonary parenchyma– Lung patterns
• Heart• Trachea• Mediastinum• Pleural space
Donuts and Tramtracks, Oh my!
• Bronchial Pattern – Airway inflammation!!!– Chronic bronchitis– Age-related change– Infectious disease
• Parasitic (heart/lungworm)• Fungal (less likely)
– PIE – Irritant (smoke)– Allergic
Trees in the Fog – A Davis Winter
• Alveolar Pattern– Bronchopneumonia– Edema– Atelectasis– Hemorrhage– Mass – Histiocytic sarcoma– Torsion/infarct
• Location and character Air bronchogram
Lobar Sign
Surrounding Vessels
Alveolar Pattern Not an Alveolar Pattern!
Interstitial PatternUnstructured• Underexposure• Underinflated lungs• Obesity• Age-related changes• Disease in transition
– Edema– Hemorrhage– Bronchopneumonia
• Lymphoma• IPF in terriers• Pneumonitis
– Parasitic– Viral pneumonia– Inhalation (smoke, etc)– Toxic (paraquat)– Metabolic (uremia, etc)
Structured (nodular)• Neoplasia
– Primary lung tumor– Metastasis
• Granuloma– Fungal– Eosinophilic– Parasitic
• Abscess - FB• Bulla• Hematoma• Mucus-filled bronchus• Artifact
Unstructured Interstitial Pattern
• Description– Generalized increased opacity– Hazy– Poorly-defined vascular borders
• Non-specific pattern– MUST correlate to clinical signs
Miliary Pattern
Miliary Pattern
Vascular Pattern
Pulmonary Parenchyma
• Rules to live by:– The predominant (and worst) pattern wins– Not every pattern is clear– Interstitial is everything else– Three views for all– Don’t forget the cervical region
Bronchointerstitial Pattern
Heart versus Lung Disease• Important Questions:
– Degree of cardiomegaly?• Exception: ruptured chordae tendinae
– Enlarged pulmonary vessels?– Left atrial impingement on airways?– Auscultation findings?
Ruptured Chordae Tendinae - Before
Ruptured Chordae Tendinae - After
Trachea• Trachea
– Anatomy– Collapse– Displacement/Compression– Stricture
• Neoplasia, granuloma, fibrous, FB, polyp
– Tracheitis• Very common clinically• Poorly identified on rads
Tracheal Anatomy
Breed Differences
Tracheal Collapse• Chondromalacia
– Often seen in association with:• Mainstem bronchi collapse• Lower airway inflammation – chronic bronchitis
• Fat old small breed dogs• Redundant tracheal membrane
– Exception – Grade I “collapse”• Dynamic process
– Lack of radiographic sensitivity– Mainstem bronchi– Fluoroscopy
Redundant Tracheal Membrane
Tracheal Displacement/Compression
Tracheal Stricture
Mediastinum• Anatomy• Cause of Coughing
– Mass• Neoplasia – Lymphoma, thymoma• Hemorrhage (rodenticide)• Granuloma – crypto (esp. cats)• Branchial cyst
– Hilar lymphadenopathy• Lymphoma, fungal, PIE
– Mediastinal Shift• Atelectasis
Anatomic Differences
Mediastinal Reflections
Mediastinal Masses• Causes cough by tracheal impingement• Cranial Mediastinum
– Radiographic signs• Widened mediastinum (DV/VD)• Tracheal deviation
– Dorsal or lateral• Caudal cardiac/hilar deviation
– Normal: 5th/6th thoracic vertebra level• Pleural effusion
– Often seen with mediastinal masses– Should not cause tracheal elevation by itself (dogs)
Hilar Lymphadenopathy
• Radiographic findings:– Cowboy sign– Increased perihilar density– Deviation of the trachael carina
• Usually ventral or unchanged
• Hilar lymphadenopathy vs large LA– LA: dorsal tracheal elevation– LA: overall heart size is also increased
Hilar Lymphadenopathy
Cowboy Sign Mediastinal Shift
Pleural Space
• Pleural disease alone• Underlying pulmonary disease process
– Pyothorax• FB pneumonia• Pulmonary abscess (hematogenous, penetrating)
• Neoplasia• Lung lobe torsion/infarction
