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pattern develops.Airway disease
Lower airway disease can appear radiographically normal or have varying severities of airway pattern. Tracing the trachea to the carina and then tracing each main bronchus of each lobe should be performed. Two-thirds of the way out from the carina, the visualization of the bronchial walls and vessels should slowly disappear. If larger numbers of branching structures are visible, then an airway pattern is present. However, clinical signs are not always present. The clinical signs of airway disease may wax and wane, but chronic airway patterns are persistent on thoracic radiographs, regardless of clinical activity. This is where reader bias can sway the importance placed upon the presence of an airway pattern, or even lead the reader away from other abnormalities due to tunnel vision. 2 Airway disease is usually due to allergic airway disease, asthma and heartworm infection. A recent study confirmed that the most common radiographic abnormality is a bronchial pattern, but an unstructured interstitial pattern can be present in many cats. More than half of the cats in that study had lung hyperinflation also. 2 Bronchiectasis can be identified in a smaller number of cats. Right middle lobar atelectasis can be seen, as can small nodules throughout the lung and represent mucous plugs with granuloma formation.
Severe inflammatory lower airway disease can lead to hyperinflation with a flattened diaphragm. The bronchial pattern can be mixed with small nodules due to mucous plugging and exudates.
Interstitial lung disease
Primary Neoplasia
Pulmonary Fibrosis
Pulmonary fibrosis is a progressive fatal interstitial lung disease that is often idiopathic, occurs in multiple
species, and may be caused by a number of inciting factors. A recent study of nine cats showed that
all patients had a broad range of radiographic characteristics that included broncho-interstitial pattern, alveolar pattern, pulmonary masses, pulmonary bullae, pleural effusion, and cardiomegaly. 5 Cats in that study with echocardiographic studies had characteristics
that included right ventricular dilation and hypertrophy and pulmonary arterial hypertension interpreted to be secondary to primary lung disease. Cats with pulmonary fibrosis have highly variable radiographic characteristics and that these characteristics may mimic other diseases such as asthma, pneumonia, pulmonary edema, or neoplasia. 5
Vascular Disease
Heartworm disease can cause enlarged pulmonary arteries. However, the pulmonary findings may also be rather unremarkable in infected cats. An airway pattern is often present in most cases as well. Cardiac abnormalities are not typical.
[1] Dennler M, Bass DA, Gutierrez-Crespo B, Schnyder M, Guscetti F, Di Cesare A, Deplazes P, Kircher PR, Glaus TM: Thoracic computed tomography, angiographic computed tomography, and pathology findings in six cats experimentally infected with Aelurostrongylus abstrusus. Veterinary radiology & ultrasound: the official journal of the American College of Veterinary Radiology and the International Veterinary Radiology Association 2013, 54:459-69.
[2] Gadbois J, d’Anjou MA, Dunn M, Alexander K, Beauregard G, D’Astous J, De Carufel M, Breton L, Beauchamp G: Radiographic abnormalities in cats with feline bronchial disease and intra- and interobserver variability in radiographic interpretation: 40 cases (1999-2006). Journal of the American Veterinary Medical Association 2009, 234:367-75.
[3] Aarsvold S, Reetz JA, Reichle JK, Jones ID, Lamb CR, Evola MG, Keyerleber MA, Marolf AJ: Computed tomographic findings in 57 cats with primary pulmonary neoplasia. Veterinary radiology & ultrasound: the official journal of the American College of Veterinary Radiology and the International Veterinary Radiology Association 2015, 56:272-7.
[4] Goldfinch N, Argyle DJ: Feline lung-digit syndrome: unusual metastatic patterns of primary lung tumours in cats. Journal of feline medicine and surgery 2012, 14:202-8.
[5] Evola MG, Edmondson EF, Reichle JK, Biller DS, Mitchell CW, Valdes-Martinez A: Radiographic and histopathologic characteristics of pulmonary fibrosis in nine cats. Veterinary radiology & ultrasound: the official journal of the American College of Veterinary Radiology and the International Veterinary Radiology Association 2014, 55:133-40.
Primary pulmonary neoplasia is relatively
uncommon in cats and generally has a poor
prognosis. Radiographically it is typically a solitary
or multiple masses, or, a disseminated lung pattern
or lobar consolidation that looks like pneumonia. Adenocarcinoma may be come cavitated. Bronchoalveolar cell carcinomas and squamous cell carcinoma are usually diffuse in the lung. Most pulmonary tumors are in the caudal lobes. Adenocarcinoma is reported as the predominant tumor type, but shares many features with less common tumor types. Prevalence of suspected intrapulmonary metastasis was higher than in previous radiographic studies of cats with lung tumors. 3
Metastatic neoplasia
Metastatic neoplasia generally present as multifocal small round soft tissue pulmonary nodules. In cats, lung-digit syndrome is an unusual pattern of metastasis that is seen with various types of primary lung tumors, particularly bronchial and bronchioalveolar adenocarcinoma. Tumor metastases are found at atypical sites, notably the distal phalanges of the limbs; the weight bearing digits are most frequently affected, and multiple-digit and multiple- limb involvement is common.4

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