Topography
Each lung fills its pleural cavity, from the pleural cupula at the level of the first rib to the diaphragm. The mediastinum between them holds the heart, trachea and esophagus. The feline mediastinum is thin and often incomplete, so pneumothorax and pleural effusions are usually bilateral. Caudal to the basal border of the lungs, the costodiaphragmatic recess of the pleura contains no lung.
Lobes
- Left lung: cranial lobe (with cranial and caudal parts) and caudal lobe.
- Right lung: cranial, middle, caudal and accessory lobes. The accessory lobe sits in the mediastinal recess, around the caudal vena cava.
Clinical relevance
- Feline asthma: eosinophilic inflammation of the lower airways with bronchoconstriction. Radiographs show a bronchial pattern, hyperinflation with a flattened diaphragm and, sometimes, collapse of the right middle lobe.
- Heart failure: in the cat pulmonary oedema has a patchy distribution and is often accompanied by pleural effusion.
- Pleural effusion: common feline causes are heart failure, pyothorax, feline infectious peritonitis and mediastinal lymphoma. Thoracocentesis is done at about the 7th–8th intercostal space.
- High-rise syndrome: falls from height cause pulmonary contusion and pneumothorax.
- Aspiration pneumonia: typically affects the cranioventral lobes.
- Pulmonary carcinoma: in the cat it can metastasise to the digits (lung-digit syndrome) and present as lameness.
- Parasites: Aelurostrongylus abstrusus causes a bronchointerstitial pattern that can be mistaken for asthma.
3D model
Schematic shape (illustrative fidelity), placed from landmarks on the skeleton and the scanned organs. The lobes are not separated. It shows topography, not fine morphology.