Interpretation of Pulmonary Patterns in Cats

• The normal lung
  • Characterised by sharp defined borders of the diaphragm and lung, heart and lung, and vascular structures and the lung
  • The peripheral lung fields have very little structure, and are typically radiolucent
  • On the VD view, look lateral to the caudal bronchi to assess pulmonary arterial vascular size
• Bronchocentric lung pattern
  • Note that the bronchocentric pattern can involve diseases not only of the bronchial wall, but also the lymphatics and blood vessels – meaning that diseases affecting vasculature and interstitium can result in a bronchocentric pattern.
  • This lung pattern is characterised by
    • Increased number of rings and lines – often extending to the periphery of the lung field – where in the normal cat, there is usually no specific structures visible, and are typically very radiolucent.
    • Lobar collapse – characterised by collapse of one or more lung lobes due to reduced lung inflation secondary to bronchial narrowing
    • Bronchial mineralisation
    • Bronchiectasis
    • Pulmonary hyperinflation – leading to increased lung size, and caudal displacement of the diaphragm
    • Spontaneous rib fractures
    • Effacement of the caudal vena cava, and blurring of the borders of the diaphragm, heart and major vessels with the lung tissue may also observed
  • Causes of bronchocentric lung pattern include
    • Allergic airway disease
    • Infectious courses, including bacterial, fungal and parasitic
• Pulmonary Hypertension/pulmonary thromboembolism
  • May be characterised by vascular enlargement (arterial) followed by lung lobe consolidation, atelectasis and collapse
• Diffuse complex lung patterns
  • Frequently the result of interstitial lung disease
  • This lung pattern is characterised by
    • Often lead to loss of normal structures within the lung
    • Often lead to loss of normal sharp margins between diaphragm, heart and vascular structures and the lung tissue
    • May be diffuse, nodular or patchy
  • Causes include
    • Infectious (parasitic, fungal, bacterial), inflammatory, idiopathic
    • Neoplastic
    • Idiopathic feline pulmonary fibrosis
• Diffuse “foggy” lung pattern
  • Think lymphatic disease
  • Subclassification of a diffuse hazy interstitial lung pattern
  • Causes include lymphoma
• Alveolar consolidation
  • Differential diagnoses include
    • Pneumonia
    • Haemorrhage
    • Oedema
    • Atelectasis – caused by airway disease, mucous plugging etc.
• Multifocal pulmonary nodules
  • Causes include
    • Metastatic neoplasia
    • Granulomas due to chronic mucous plugging
    • Fungal and parasitic infections
• Cavitary masses
  • Central region of necrosis leading to gas production, surrounded by a “capsule”
  • Causes include
    • Pulmonary carcinoma
    • Abscessation
    • Parasitic cysts
    • Granulomas
  • Check the toes – for lung digit syndrome – due to micrometastatic disease in the distal extremities

This is an outstanding lecture, full of practical tips, and is recommended viewing for anyone wishing to improve their pulmonary radiographic interpretation skills!