This document provides guidance on evaluating radiographic findings related to coughing in dogs. It discusses evaluating the pulmonary parenchyma, heart, trachea, mediastinum, and pleural space. Specific patterns like bronchial, alveolar, interstitial, and lobar patterns are described. Differential diagnoses for various abnormalities are provided. The importance of systematic evaluation and correlating radiographic findings with clinical presentation is emphasized.

1. The Radiographic Approach to
the Coughing Dog
Matthew Cannon, DVM DACVR
Pixel Veterinary Imaging
Austin, TX

2. 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

4. Potential Sources
• Pulmonary parenchyma
– Lung patterns
• Heart
• Trachea
• Mediastinum
• Pleural space

5. 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

10. Trees in the Fog – A Davis Winter
• Alveolar Pattern
– Bronchopneumonia
– Edema
– Atelectasis
– Hemorrhage
– Mass – Histiocytic sarcoma
– Torsion/infarct
• Location and character Air bronchogram

12. Lobar Sign

13. Surrounding Vessels
Alveolar Pattern Not an Alveolar Pattern!

14. Interstitial Pattern
Unstructured
• 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

15. Unstructured Interstitial Pattern
• Description
– Generalized increased opacity
– Hazy
– Poorly-defined vascular borders
• Non-specific pattern
– MUST correlate to clinical signs

19. Miliary Pattern

20. Miliary Pattern

21. Vascular Pattern

23. 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

24. Bronchointerstitial Pattern

25. Heart versus Lung Disease
• Important Questions:
– Degree of cardiomegaly?
• Exception: ruptured chordae tendinae
– Enlarged pulmonary vessels?
– Left atrial impingement on airways?
– Auscultation findings?

29. Ruptured Chordae Tendinae - Before

30. Ruptured Chordae Tendinae - After

31. Trachea
• Trachea
– Anatomy
– Collapse
– Displacement/Compression
– Stricture
• Neoplasia, granuloma,
fibrous, FB, polyp
– Tracheitis
• Very common clinically
• Poorly identified on rads

32. Tracheal Anatomy

33. Breed Differences

34. 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

35. Redundant Tracheal Membrane

38. Tracheal Displacement/Compression

40. Tracheal Stricture

41. 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

42. Anatomic Differences

43. Mediastinal Reflections

44. 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)

47. 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

48. Hilar Lymphadenopathy

49. Cowboy Sign Mediastinal Shift

50. Pleural Space
• Pleural disease alone
• Underlying pulmonary disease process
– Pyothorax
• FB pneumonia
• Pulmonary abscess (hematogenous, penetrating)
• Neoplasia
• Lung lobe torsion/infarction

53. Question!
• Feel free to contact me anytime:
– cannon.vetrad@gmail.com
– 512-534-8414
– Pixelvetimaging.com