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The lung parenchyma

image of The lung parenchyma
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Abstract

Dogs and cats have two lungs, which are not symmetrical in terms of size and lobation. The lobar anatomy is based on the bronchial division. The chapter is divided into the following sections: Radiographic anatomy; Interpretive principles and Diseases.

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Figures

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12.1 VD thoracic radiograph of a dog showing the lung lobes. Right lateral thoracic radiograph of a dog showing the left lung lobes. Left lateral thoracic radiograph of a dog showing the right lung lobes. Acc = Accessory lung lobe; LeCd = Left caudal lung lobe; LeCr1 = Cranial segment of the left cranial lung lobe; LeCr2 = Caudal segment of the left cranial lung lobe; RtCd = Right caudal lung lobe; RtCr = Right cranial lung lobe; RtM = Right middle lung lobe.
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12.2 Close-up of a lateral thoracic radiograph at the level of the first ribs of a dog. The cranial tip of the left cranial lung lobe (black arrows) is seen as a round lucency in the pleural cupula, cranial to the first pair of ribs. It is separated from the remainder of the lung by a soft tissue opaque band, which represents a mediastinal fold (white arrow).
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12.3 Lateral thoracic radiograph of a Domestic Shorthair cat with a relatively radiolucent area ventral to the cardiac silhouette. The visible bronchovascular structures (arrowheads) indicate that this is inflated lung and not pleural free gas.
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12.4 Lateral thoracic radiograph of a dog with superimposed lung fields. Caudodorsal = Blue; Caudoventral = Green; Cranioventral = Yellow; Perihilar = Red.
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12.5 Cranioventral close-up of a lateral thoracic radiograph of a 6-year-old Briard. The lungs appear almost as lucent (dark) as the air outside of the patient (lower left corner). Air does not attenuate the X-ray beam, and inflated lung mainly consists of air. Visible pulmonary structures include lung vessels in side-on (white arrowheads) or end-on (black arrowheads) orientation, and mineralized bronchial walls (arrowed). Close-up of a lateral radiograph of normal lung tissue caudodorsal to the carina (C). First- to third-order vascular branches and mineralized bronchi are easily distinguishable. A reticular (mesh-like) pattern of increased opacities is seen dorsally, created by small vessels and interstitium. The superimposed descending aorta contributes an additional homogenous increase in opacity to the upper half of the image.
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12.6 Close-up of a VD thoracic radiograph of the left caudal lung field of a dog. A triad of artery (black arrowhead), bronchus (arrowed) and vein (white arrowhead) can be seen (viewed end-on) with the vein at a small distance from the bronchus.
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12.8 Normal left lateral thoracic radiograph of a 5-year-old Bull Mastiff with annotations for: the main bronchus for the right cranial and middle lung lobes (yellow); the main bronchus for the cranial and caudal segments of the left cranial lung lobe (light blue); the associated pulmonary arteries (orange); and the associated pulmonary veins (blue). Notice the more dorsal location of the origin of the right stem bronchus compared with the left one, which is used as a landmark. The two most cranially oriented bronchi are accompanied dorsally by the artery, and ventrally by the vein. Maximal normal diameter of the cranial lung lobe vessels should not exceed the width of the proximal third of the fourth rib (arrowed). Close-up of a DV thoracic radiograph of the right caudal thorax in a dog. The artery (red arrow) and vein (blue arrow) of the right caudal lung lobe are smaller than the width of the ninth rib where they intersect (yellow arrow).
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12.9 Lateral thoracic radiograph of a normal dog obtained at peak inspiration. The lungs are expanded, separating the cardiac and diaphragmatic silhouettes and opening the lumbodiaphragmatic recess beyond the thirteenth thoracic vertebra. Cardiovascular structures appear relatively small. The net result is relatively radiolucent lung tissue. Lateral thoracic radiograph obtained during the expiratory pause. Due to lung retraction, the cardiac and diaphragmatic silhouettes overlap, the lumbodiaphragmatic recess only extends to the twelfth thoracic vertebra, and the cardiovascular structures appear bigger. The resulting lung opacity is markedly increased, yet it is normal for this phase of respiration.
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12.10 Ventral close-up of a lateral thoracic radiograph of a West Highland White Terrier with annotated ventral lung margins. Cranial and caudal lung margins (red lines) extend to the ventral thoracic boundaries. The mid section of the lung only extends to the level of the ventral aspect of the cardiac silhouette with a wavy margin (blue line). This is a sign of normal incomplete lung lobe inflation with or without peripheral lung collapse.
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12.11 VD thoracic radiograph of a 4-month-old Abyssinian cat. The lung opacity is relatively high for the size of the animal but normal for its age and expiratory phase.
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12.12 Close-up of a lateral thoracic radiograph of a 9-year-old English Springer Spaniel with heterotopic pulmonary bone formation, manifesting as round mineral opacities throughout the lungs. The opacities ranged in size from 1–3 mm.
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12.13 Close-up of a lateral radiograph of the caudodorsal lung margin of a 4-year-old Whippet at peak inspiration. The dorsal lung margins are superimposed on the thoracic vertebrae (arrowheads) and the lung expands to the level of the last thoracic vertebra. Close-up of a lateral radiograph of the caudodorsal lung margin of an 18-year-old Domestic Shorthair cat at peak inspiration. The caudodorsal lung margin is separated from the spine by the psoas minor muscle. The lung expands to the level of the first lumbar intervertebral disc space. (Courtesy of C. Jarrett)
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12.14 DV thoracic radiograph of an obese small-breed dog. Note the relatively high lung opacity due to the large amount of superimposing subcutaneous fat. Large amounts of fat are also accumulated in the cranial mediastinum and pericardium, which further restricts full lung expansion.
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12.15 Lung volumes as they appear on a lateral thoracic radiograph of a dog. A normal expiratory radiograph is taken with the lung in functional residual capacity (FRC, small black arrow). At peak inspiration, the tidal volume (TV, between large black arrows) is added. With hyperinflation (stressed animal, air trapping), the inspiratory reserve volume (IRV, between large white arrows) is added and the lung reaches total lung capacity (TLC), deviating the diaphragm caudally. With forced expiration, the FRC may be reduced by the expiratory reserve volume (ERV) to reach the reserve volume (RV, small white arrow) of the lung. If the lung is compressed (mass, increased intrapleural pressure) it can become totally atelectatic (TA). (Reproduced from with permission)
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12.16 Inspiratory lateral thoracic radiograph of a cat with asthma. The lungs are hyperlucent and the pulmonary vessels and cardiac silhouette are small (vertebral heart score 7). The lung fields are enlarged. The diaphragmatic silhouette is deviated far caudally from the cardiac silhouette and appears flattened. The caudodorsal lung margins open the lumbodiaphragmatic recess and extend caudally to the level of L2. The barely visible caudal vena cava (between arrowheads) is small. The stomach is gas-distended (aerophagia). If the lungs remain hyperlucent and enlarged at expiration, air trapping is a likely cause, consistent with bronchiolar disease.
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12.17 Inspiratory lateral thoracic radiograph of a 7-week-old kitten with pectus excavatum, a chest wall anomaly. The caudodorsal lung fields are increased in opacity due to the restricted chest wall expansion, prohibiting full lung inflation.
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12.18 Histological image of a canine lung. For the purpose of radiographic evaluation the lungs can be interpreted as the sum of the vessels (V), bronchi (B), alveolar airspace (A) and pulmonary interstitium (I). H&E stain; original magnification x160.
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12.19 Histological image of a canine lung demonstrating the concept of an alveolar lung pattern. The alveolar air has been replaced by more opaque structures (grey area) either due to airspace compression or filling. The encroached air-filled bronchi could create air bronchograms. H&E stain; original magnification x160.
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12.20 VD thoracic radiograph of a 1-year-old Bichon Frisé with pulmonary haemorrhage due to rodenticide intoxication. The right lung is homogenously opacified to a similar degree as the soft tissue organs, such as the heart and liver. Several radiolucent bands can be seen within the opacified lung, representing air bronchograms (arrowheads). The cardiac silhouette is slightly shifted towards the right, indicating some loss of normal right lung volume. Both the cardiac silhouette and the right hemidiaphragm are partially obliterated by the lung (border obliteration sign). These are all classic features of the alveolar lung pattern. The left lung appears hyperinflated and hyperlucent, indicative of compensatory hyperinflation.
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12.21 Lateral thoracic radiograph of a 5-year-old Labrador Retriever with traumatic chordae tendinae rupture and mitral valve regurgitation with secondary cardiogenic pulmonary oedema. There is increased lung opacity with the alveolar pattern in the perihilar lung region, with indistinct margination towards the lung areas with an interstitial pattern (caudal) and a normal appearance (ventral) in the lung periphery. The marked pulmonary oedema combined with the mild left atrial enlargement is consistent with the recent traumatic history. (Courtesy of P. Wotton)
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12.22 VD thoracic radiograph of a 6-year-old Briard with pneumonia. Only the right middle lung lobe is affected and shows the alveolar lung pattern. There is border obliteration with the cardiac silhouette, some air bronchograms, and distinct margination towards the normally aerated right cranial and caudal lung lobes (lobar sign). The cardiac shadow is completely confined to the right hemithorax, indicating mediastinal shift due to right middle lung lobe collapse. Compensatory hyperinflation of the left lung is present.
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12.23 VD thoracic radiograph of an 8-year-old Cocker Spaniel with bronchoalveolar carcinoma. The mainly affected left lung is increased in opacity with an alveolar pattern and increased in volume, indicated by the deviation of the cardiac silhouette into the right hemithorax (arrowheads).
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12.24 Caudodorsal close-up of a lateral thoracic radiograph of a 2-year-old Mastiff with vegetative endocarditis and secondary pneumonia and pulmonary oedema. There is generalized increased lung opacity, created by the partially obliterated alveolar airspace (partial alveolar pattern). Particularly in the more ventral lung fields, vessels are no longer distinguishable and air bronchograms begin to emerge; however, the opacity is still inhomogenous due to residual air-filled alveoli (air alveolograms), giving the image a ‘salt-and-pepper’ appearance. Thin pleural fissure lines are visible superimposed over the caudal cardiac silhouette.
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12.25 Histological image of a canine lung demonstrating the concept of the bronchial lung pattern. Bronchial walls (outlined ring structures) create an increased lung opacity by virtue of wall thickening or extensive wall mineralization. H&E stain; original magnification x160.
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12.26 Caudodorsal close-up of a lateral thoracic radiograph of a 14-year-old Domestic Shorthair cat with asthma. There is an increased lung opacity, predominantly created by the bronchial structures (bronchial pattern). It can be difficult to differentiate normal vessels from abnormal bronchi. The presence of ring shadows (‘doughnuts’) indicates bronchial origin. Further close-up reveals thickened bronchi in both long axis (tram lines, arrowed) and short axis (ring shadows, arrowhead).
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12.27 Close-up of a lateral thoracic radiograph of a 9-year-old Standard Poodle with hyperadrenocorticism, causing excessive widespread bronchial mineralization. Increased lung opacity results from the bronchi that are more opaque, but not thicker, than normal (bronchial pattern). (Reproduced from with permission from the )
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12.28 Histological image of a canine lung demonstrating the concept of a vascular lung pattern. Pulmonary vessels (outlined) create an increased lung opacity by virtue of wall thickening or distension. H&E stain; original magnification ×160.
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12.29 Caudodorsal close-up of a lateral thoracic radiograph of a 9-month-old German Shepherd Dog with a patent ductus arteriosus and left-to-right shunt, resulting in pulmonary hyperperfusion. There is increased lung opacity due to numerous distended pulmonary vessels (vascular pattern). A distinction between arteries and veins cannot be made in this region on this view. The left atrium is enlarged due to volume overload.
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12.30 Histological image of a canine lung demonstrating the concept of an interstitial lung pattern. A thickened pulmonary interstitial space (outlined) creates an increased lung opacity. Since the alveolar airspace remains intact, small lung vessels will still be sufficiently outlined by air to be visible. The interstitium is the weakest contributor to lung opacification. If combined with other compartment disorders, which is often the case, other patterns are usually predominant. H&E stain; original magnification x160.
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12.31 VD thoracic radiograph of a 13-year-old Cocker Spaniel with ocular melanoma and metastatic lung disease. There is an increased lung opacity created by numerous pulmonary soft tissue nodules of various sizes (nodular pattern). In some parts, the nodular shadows coalesce.
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12.32 Lateral thoracic radiograph with a caudal close-up of a 9-year-old Golden Retriever with a heart base mass and miliary pulmonary metastases. There is increased lung opacity created by very many small soft tissue nodules (miliary nodular pattern) that superimpose on each other and coalesce. The close-up image demonstrates more clearly the nodular nature of the opacity.
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12.33 Caudodorsal close-up of a lateral thoracic radiograph of a dog with histoplasmosis. There is increased lung opacity created by numerous 2–4 mm mineralized nodules throughout the lungs (nodular pattern). The combination of small nodular size and high opacity would make these lesions unlikely candidates for metastatic neoplasia.
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12.34 Caudodorsal close-up of a lateral thoracic radiograph of a 3-year-old German Shepherd Dog with lymphoma. There is a mild increase in lung opacity, diffusely spread over the lung fields. This opacification is caused by interstitial infiltration of the lymphoma. Given the well inflated state, and appropriate exposure settings, such lung opacity can be classified as abnormal and other patterns can be ruled out based on appearance. The fact that small lung vessels are still visible is an indicator for the interstitial pattern.
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12.35 Caudodorsal close-up of an inspiratory lateral thoracic radiograph of an 8-year-old Siamese cat with asthma. There is increased lung opacity, created by numerous thickened bronchi and a superimposed veil of diffuse opacification. This can be called a . The bronchial component is predominant, as well as more specific, and should be focused on for diagnosis, prognosis and treatment.
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12.36 Cranioventral and caudodorsal lung fields. Clinically normal right lateral thoracic radiograph of a dog. A line is drawn to indicate the approximate demarcation of the cranioventral and caudodorsal lung fields. Note that the cranioventral lung field extends to the most caudoventral aspect of the thorax, and is superimposed on the heart. This is important because the most common location for aspiration pneumonia is in the cranioventral lung field superimposed on the heart.
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12.38 Central close-up of a right lateral thoracic radiograph of a 12-year-old German Shepherd Dog with a pulmonary carcinoma. The mass slightly deviates the air-filled left cranial lung lobar bronchus but does not give rise to an air bronchogram. This indicates that the mass is of an expansile rather than infiltrative nature. CT image confirms how the mass abuts but does not encroach into the bronchus. (Courtesy of L. Jarrett)
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12.39 Close-up of a DV thoracic radiograph of a dog with a histiocytic sarcoma in the right middle lung lobe. The mass occupies a large portion of the lobe, giving rise to a lobar sign cranially and caudally, and contains air bronchograms. This is consistent with an infiltrative lesion encroaching on the airways. Caudal close-up of a VD thoracic radiograph of a 12-year-old Domestic Shorthair cat with nasal and pulmonary lymphoma. Notice the increased opacity with an alveolar pattern (air bronchogram) supportive of an infiltrative process. Radiographically evident pulmonary involvement in feline lymphoma is extremely rare.
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12.40 Left lateral thoracic radiograph of a 12-year-old mixed breed dog with primary bronchoalveolar carcinoma. A solitary nodule with soft tissue opacity is seen in the right middle lung lobe (arrowed).
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12.41 VD thoracic radiograph of an 8-year-old Rottweiler with pulmonary adenocarcinoma. There is a mass with soft tissue opacity in the left caudal lung lobe. Note the border obliteration between the mass and the heart.
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12.42 VD thoracic radiograph of a 12-year-old Bichon Frisé with primary pulmonary carcinoma. The entire left cranial lung lobe is consolidated.
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12.43 Craniodorsal close-up of a right lateral thoracic radiograph of a 10-year-old Domestic Shorthair cat with a primary lung lobe tumour in the left cranial lobe. There are multiple small mineralizations in the craniodorsal lung fields. A VD view confirmed their location within the left cranial lung lobe.
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12.44 Close-up of a radiograph of the third phalanx of the fifth digit of the right manus of a 9-year-old Rottweiler with digital pain. Notice the soft tissue swelling and extensive osteolysis of P3 (histological diagnosis: subungular melanoma).
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12.45 Left lateral thoracic radiograph of a 1-year-old Great Dane with suppurative pneumonia. A cavitary mass (M) is seen in the right cranial lung lobe. The centrally present gas delineates a thick wall with an irregular inner surface. The caudally adjacent right middle lung lobe is increased in opacity with an alveolar pattern (air bronchograms, lobar sign), consistent with pneumonia.
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12.46 Ventral close-up of a lateral thoracic radiograph of a 3-year-old mixed breed dog with granulomatous fungal pneumonia. There are multiple small soft tissue nodules throughout the lungs (arrowed). There is also hilar lymphadenopathy, evident by the increased opacity dorsal to the heart base.
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12.47 Lateral thoracic radiograph of a 6-year-old Rottweiler with pulmonary infiltration and eosinophilia. There is increased lung opacity with a mixed pattern of bronchial and alveolar disease. Note the nodular component (arrowed) caused by the formation of granulomas.
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12.48 Close-up of a lateral oesophagram of a 14-year-old Boxer with a perihilar mass. Barium outlines the oesophageal mucosa cranial and caudal to the mass with a normal pattern (bolus at the gastro-oesophageal sphincter and position), making an oesophageal lesion unlikely. Final diagnosis was bronchial adenocarcinoma. (Courtesy of the University of Pennsylvania)
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12.49 Close-up of a bronchogram of the left lung of an 8-year-old English Springer Spaniel with bronchial adenocarcinoma arising from the left mainstem bronchus. Survey radiographs showed a hilar soft tissue mass. The contrast study demonstrates the central filling defect resulting from the mass and residual patency, allowing filling of peripheral bronchi with contrast medium. Bronchography has been superseded by bronchoscopy and CT. (Courtesy of the University of Pennsylvania)
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12.50 Ultrasonographic thoracic linear transducer image of a 5-year-old Domestic Shorthair cat with a primary lung tumour. The affected lung lobe has lost its normal reflectivity and appears with the echogenicity of soft tissue. Residual amounts of trapped air are hyperechoic and cause dirty shadowing distally (arrowhead). Note also the small amount of anechoic pleural effusion (arrowed).
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12.51 Ultrasonographic thoracic curvilinear transducer image of a 2-year-old Weimaraner with a lung abscess. Adjacent to the pleural lung margin, there is a round mass with a thick echoic capsule with irregular internal margins and a hypoechoic core. The hyperechoic area around the mass represents normal aerated lung.
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12.52 Post-contrast CT image at a level immediately caudal to the carina of a 7-year-old Bulldog with a primary pulmonary carcinoma. A large soft tissue attenuating mass (M) is displacing the heart (H) and major vessels towards the left, and deviating and compressing the right middle lung lobe (L) and its bronchus. There is heterogenous mild enhancement of the mass with rim enhancement, and strong enhancement of the collapsed lung. Ventrally viewed 3D reconstruction with the air-filled spaces in white. A large void in the right lung corresponds to the tumour and atelectatic lung tissue. (Courtesy of J. Kinns) Post-contrast CT image of the caudal thorax of a 2-year-old English Cocker Spaniel with a lung abscess. There is a hypoattenuating mass in the right caudal lung lobe (A), with a thick, mildly enhancing capsule. The liver (L) and hypoattenuating gallbladder (G) are seen ventrally. Note the complete flattening of the contrast-enhanced caudal vena cava (arrowhead) due to compression by the mass.
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12.53 High-resolution thoracic CT image at the level of the aortic arch of the same dog as in Figure 12.46 with granulomatous pneumonia. Note the soft tissue attenuating nodules in the peripheral lung (arrowheads). These can be differentiated from vessels by their larger size in the peripheral lung, and by evaluating contiguous images (vessels can be followed cranially and caudally).
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12.54 Lateral thoracic radiograph of a 4-year-old Rottweiler with metastatic pulmonary disease from an unidentified primary neoplasia. Note the numerous, round, relatively well marginated nodules, with soft tissue opacity of variable size throughout the lungs.
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12.55 Close-up of a lateral thoracic radiograph of a 12-year-old Domestic Longhair cat with metastatic pulmonary neoplasia. Compared with the dog in Figure 12.54 , the nodules are ill defined and not round. This is a relatively common appearance of metastatic nodules in cats.
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12.56 Caudodorsal close-up of a lateral thoracic radiograph of a 10-year-old Papillon with pulmonary metastases from a splenic haemangiosarcoma. There are multiple poorly defined small coalescing nodules spread throughout the lungs.
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12.57 Ultrasonographic thoracic curvilinear transducer image of a 9-year-old Boxer with a neuroendocrine heart base tumour and metastatic pulmonary disease. The peripheral metastatic nodule is round and hypoechoic with a small hyperechoic core, and smooth margins surrounded by hyperechoic aerated lung.
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12.58 Central close-up of a right lateral thoracic radiograph of a 9-year-old mixed breed dog taken 3 months after removal of the right middle lung lobe with a pulmonary carcinoma. Notice the surgical staples (black arrowhead) and a faintly visible nodular opacity (white arrowhead). The opposite lateral film was unremarkable. High-resolution thoracic CT image at the level of the tracheal bifurcation. There is a soft tissue nodule in each cranial lung lobe (6 mm right, 9 mm left diameter) and ventral recumbency-related atelectasis. High-resolution thoracic CT image at the level of the accessory lung lobe of a 7-year-old mixed breed dog with anal sac adenocarcinoma and pulmonary metastases. Multiple nodules, 1–4 mm in size, are visible throughout the lungs. Nodules in the lung periphery are easily identified whereas more central lesions must be distinguished from normal lung vessels with slice-by-slice comparison. Such nodules appear similar to granulomatous soft tissue nodules (see Figure 12.53 ) and must be evaluated in conjunction with the clinical history and disease progression.
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12.59 High-resolution thoracic CT image at the level just caudal to the carina of a 9-year-old Labrador Retriever with a nasal adenocarcinoma. There are numerous 1 mm mineralized ditzels throughout the lungs. These are incidental osteomas and not neoplastic metastases. Nasal neoplasia rarely metastasizes to the lungs, and pulmonary metastases only very rarely mineralize.
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12.60 Dorsal plane reconstruction of a high-resolution thoracic CT image of a 13-year-old West Highland White Terrier with idiopathic pulmonary fibrosis. There is a 4 mm soft tissue nodule, including a lucent bronchus, in the cranial aspect of the left lung (arrowhead). The fact that this nodule encroaches a bronchus makes it an unlikely candidate for metastasis. A follow-up investigation showed no progression of the lesion.
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12.61 High-resolution thoracic CT image at the level of the accessory lung lobe of an 11-year-old Bichon Frisé with an anaplastic carcinoma in its left cranial lung lobe, causing complete consolidation of that lobe (L) and deviation of the heart (H). There is distinct bronchial wall thickening in the left caudal lung lobe (compared with the right). Subsequent investigation confirmed a neoplastic peribronchial infiltrate. Close-up of a CT image at the level of the accessory lung lobe of an 11-year-old Cairn Terrier with adrenal carcinoma and pulmonary carcinosis, with widespread infarction of pulmonary capillaries and tributary lung tissue. Notice the multiple, small, wedge-shaped, subpleural lesions with pleural retraction and ill defined parenchymal lesions consistent with infarct, and ventral areas of non-specific ground-glass opacity.
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12.62 Different types of pulmonary bullae. The internal and external layers of the visceral pleura (marked as black and grey, respectively) are not dissected by bullae but can be herniated in different ways. A is a round gas accumulation within the herniated visceral pleura, with a small isthmus to the pulmonary parenchyma. They are usually found at the lung apices. These bullae macroscopically resemble blebs, except that blebs are usually not spherical. A arises from subpleural parenchyma and contains emphysematous lung tissue, connected to the pulmonary parenchyma with a wider neck. A is usually a large gas pocket with or without emphysematous lung tissue deep in the pulmonary parenchyma, with possibly a more broad-based deviation of the visceral pleura. (Reproduced from with permission from the )
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12.63 Pulmonary bleb. The internal and external layers of the visceral pleura (marked as black and grey, respectively) are dissected by a gas pocket that has escaped from the pulmonary parenchyma. (Reproduced from with permission from the )
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12.64 Close-up of a lateral thoracic radiograph of a 10-year-old Labrador Retriever. Notice the round radiolucency surrounded by a thin radiopaque wall (arrowed), superimposed on the cardiac silhouette. This bulla was an incidental finding. Lateral thoracic radiograph of a 4-year-old Dobermann with spontaneous pneumothorax. Notice the large amount of free pleural gas (P) and a large ovoid gas bubble contained by a thin soft tissue rim (arrowheads) in the cranioventral lung periphery, consistent with a bleb.
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12.65 Close-up of a lateral thoracic radiograph (vertical beam) of a dog that was involved in a road traffic accident 24 hours previously. A sternal luxation, pneumothorax and multiple ovoid pulmonary soft tissue masses (arrowheads) can be identified, which could be related to the trauma or an unrelated illness. Close-up of the non-dependent hemithorax of a VD thoracic radiograph obtained with a horizontal beam. Beside the serial rib fractures (arrowheads) and free pleural gas (P) in the most elevated part of the thorax, two of the previously seen masses (M) are also visible with a straight fluid–gas interface and a thin smoothly outlined wall. These findings are most consistent with blood-filled bullae, haematoceles.
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12.66 Typification of gas- and fluid-containing lung lesions, according to gas location and fluid–gas interface. In vertical beam radiography one large central gas lucency is more likely to indicate a cyst, large abscess or bulla. Several small, irregularly shaped and distributed gas lucencies are more suggestive of neoplasia, foreign bodies or gas-producing bacteria. In horizontal beam radiography low-viscosity fluid tends to create a straight interface with gas, whereas high-viscosity fluid tends to create a convex or concave margin. Gas within solid lesions creates no interface. (Adapted and reproduced from with permission from the )
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12.67 Typification of gas-containing lung lesions, according to their wall characteristics. The wall can be regular or irregular, on either or both sides, or have a mixture of both. Smooth-walled lesions are most likely to be bullae or cysts; whereas, irregular margins are a result of tissue necrosis and infection, and are commonly seen with abscesses and neoplasms (cavitating lesions). In lesions that contain fluid and gas, these features can only be applied to horizontal beam radiographs. (Adapted and reproduced from with permission from the )
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12.68 Standing lateral horizontal beam radiograph of the caudal thorax of a 4-year-old Great Dane. The dog presented with extreme dyspnoea and coughing. A cavitating lung abscess can be seen with a horizontal fluid line (arrowed) separating the fluid from the gas. There is a marked alveolar lung pattern with a diffuse increase in soft tissue opacity of the lung fields. Close-up of a DV thoracic radiograph of an 11-year-old mixed breed dog with a chronic productive cough. The caudal part of the left cranial lung lobe has a marked increase in soft tissue opacity with retraction of the lobe edge from the thoracic wall (arrowed). There is an irregular-shaped radiolucent area eccentrically positioned within the lung lobe (arrowheads), which represents a cavitated centre. This was confirmed to be bronchogenic carcinoma with central necrosis. Lateral thoracic radiograph of a 6-year-old Domestic Shorthair cat with fluke infection. Notice the multiple pulmonary soft tissue nodules containing irregular small central air bubbles. This is a classic radiographic feature of paragonimiasis in dogs and cats.
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12.69 High-resolution thoracic CT image at the level of the accessory lung lobe of a 16-year-old Standard Poodle with numerous pulmonary bullae (*) throughout the lungs. Slice-by-slice image analysis is necessary to rule out bronchiectasis. These relatively small bullae would be difficult to identify radiographically. The interpretation of relevance of such small lesions can only be made in light of the clinical history of the patient. There is ventral hypostatic lung collapse. High-resolution thoracic CT image at the level of the aortic arch of an 8-year-old Golden Retriever with spontaneous left-sided pneumothorax (P). CT enabled identification of a leaking type 1 bulla (*) in the left cranial lung lobe. A thoracocentesis drain can be seen in cross section adjacent to the collapsed left lung.
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12.70 Expiratory lateral thoracic radiograph of a cat with asthma. Notice the small size of the cardiovascular structures, generalized bronchial lung pattern, large bulla and multiple non-union rib fractures. Caudodorsal close-up of the same radiograph reveals hyperlucent peripheral lung fields, consistent with air trapping and emphysema.
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12.71 Lateral thoracic radiograph of a 5-month-old Australian Cattle Dog with a history of chronic bronchopneumonia. Notice the multiple distended tortuous bronchi and gas pockets throughout the lungs, consistent with bronchiectasis and bullous emphysema.
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12.72 High-resolution thoracic CT image at the level of the accessory lung lobe of a 16-year-old cat with chronic lower airway disease. There are multiple soft tissue septae throughout the lungs, consistent with fibrotic changes, and focal areas of pulmonary hyperlucency consistent with emphysema (*).
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12.73 VD thoracic radiograph of an 8-year-old Jack Russell Terrier with torsion of the right middle lung lobe. There is pleural effusion in the right cranial thorax, centred around the right middle and cranial lung lobes. The right middle lung lobe is rounded and contains some air with a vesicular pattern. The cardiac silhouette appears misshapen due to a previous pericardectomy. Right lateral radiograph. There is increased lung opacity in the cranioventral thorax with air alveolograms cranially. The bronchus to the right middle lung lobe is very narrow close to the carina, and turns sharply cranially instead of caudoventrally (arrowheads), a sign consistent with lung lobe torsion.
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12.74 Left lateral radiograph of a 6-year-old Borzoi with left cranial lung lobe torsion. There is moderate pleural effusion. The carina is axially rotated, resulting in dorsal displacement of the right cranial lobar bronchus (arrowhead); a bronchus to the left cranial lung lobe is not visible. The increased opacity dorsal to the carina represents the consolidated left cranial lung lobe.
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12.75 DV thoracic radiograph of a 6-year-old Akita Inu with a left caudal lung lobe torsion. The left caudal lung lobe is enlarged, causing a mediastinal shift, and contains multiple small air bubbles (vesicular pattern).
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12.76 Thoracic curvilinear transducer ultrasound images of the same dog as in Figure 12.74 . Left oblique (intercostal) view, craniodorsal is to the left. There is marked anechoic pleural effusion and consolidation of both parts of the left cranial lung lobe with an abnormally dorsal location. Slightly more caudal image showing the periphery of the twisted left cranial lung lobe. There are large pockets of trapped gas present within the lung lobe, seen as hyperechoic areas with distal reverberation artefacts.
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12.77 Thoracic CT image at the level of the aortic root of the same dog as in Figure 12.73 . There is a mediastinal shift to the left and presence of free gas in the dorsal pleural spaces. The twisted right middle lung lobe is enlarged and partially consolidated with multiple gas pockets (*). The right cranial lung lobe is completely collapsed (arrowed) and dorsally displaced by the enlarged right middle lung lobe. Dorsal plane reconstruction of a thoracic CT image at the level of the carina of a 2-year-old Pug with chronic torsion of the right cranial lung lobe. The right cranial lobar bronchus is tapering into the consolidated lobe with a vesicular pattern.
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12.78 High-resolution thoracic CT image at the level of the accessory lung lobe of an 11-year-old Domestic Shorthair cat with a primary lung lobe tumour, leading to bronchial obstruction and collapse of the left caudal lung lobe (L). The compensatory hyperinflation of the right lung leads to mediastinal herniation of the right caudal (R) and accessory (A) lung lobes into the left hemithorax.
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12.79 Expiratory lateral radiograph of a 9-year-old Yorkshire Terrier with intrathoracic tracheal collapse. There is mild narrowing of the intrathoracic trachea. Cranial to the thoracic inlet, there are two separated lung fields protruding into the caudal cervical area (*). Only the left cranial lung lobe normally protrudes cranial to the thoracic inlet, and usually not during expiration. Expiratory VD fluoroscopic image of the thoracic inlet, demonstrating the cervical herniation of both cranial lobes (outlined). Inspiratory VD fluoroscopic view showing the cranial lung margins confined to the thoracic boundaries. This is cervical lung herniation, secondary to expiratory intrathoracic tracheal collapse and associated pressure changes.
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12.81 Lateral thoracic radiograph of a Labrador Retriever with pancreatitis. The thorax is normal. Lateral thoracic radiograph taken 48 hours later. Note the severe generalized alveolar pattern, which developed rapidly following aspiration of gastric fluid. Lateral thoracic radiograph of a 6-year-old Maine Coon cat presented with chronic coughing and dyspnoea. There are multifocal areas of ill defined soft tissue opacity in multiple lung lobes. The presumptive diagnosis was pneumonia, possibly granulomatous or atypical in origin. Open lung biopsy showed chronic inflammatory changes. Lateral thoracic radiograph following treatment with antibiotics for 3 weeks. There is no change in the lung lesions. Histopathological examination postmortem confirmed diffuse pulmonary adenocarcinoma. Lateral thoracic radiograph of an Irish Wolfhound with pulmonary oedema secondary to dilated cardiomyopathy. Lateral thoracic radiograph taken 72 hours later following treatment with diuretics. Note the resolution of the oedema in contrast to the lack of progression seen in (c) and (d). (c, d Courtesy of Cambridge Veterinary School)
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12.83 DV thoracic radiograph of a Greyhound with a simple pneumothorax following trauma. There is passive collapse of all the lung lobes. Note how the collapsed lobes maintain their shape and collapse to a similar degree (arrowheads). There is an increase in opacity within the atelectatic lung due to reduced aeration.
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12.84 VD radiograph (vertical beam orientation) of a 13-year-old Domestic Shorthair cat obtained after being under general anaesthesia in left lateral recumbency for 20 minutes. The left cranial lung lobe is collapsed with mild cardiac shift towards the left. Immediate repeat VD radiograph with the cat in right lateral recumbency (horizontal beam orientation). The non-dependent left lung is now well aerated; whereas, the dependent right middle and caudal lobes are atelectatic under the weight of the heart (hypostatic lung collapse).
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12.85 Lateral thoracic radiograph of a skeletally immature dog with a tension pneumothorax as a result of a road traffic accident. The lung lobes are significantly reduced in size and are almost as opaque as other soft tissue structures, indicating compression atelectasis.
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12.86 High-resolution thoracic CT image at the level of the accessory lung lobe of an 8-year-old mixed breed dog in dorsal recumbency under general anaesthesia, with oxygen-supplemented ventilation performed for evaluation of potential metastatic lung disease. The dorsal lung regions are collapsed and cannot be assessed for metastases. The oesophagus is gas- and fluid-distended (*). CT image at the same location from a repeat series obtained with the dog in sternal recumbency. The dorsal lung region is completely aerated again; however, the ventral tip of the right caudal lung lobe is now atelectatic. Oxygen supplementation promotes non-obstructive resorption atelectasis, particularly in the dependent lung regions (hypostatic component). Changes are quickly reversed with recumbency change, enabling diagnosis of atelectasis and assessment of the affected lung regions.
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12.87 VD thoracic radiograph of a cat with chronic bronchial disease. There is collapse of the right middle lung lobe (arrowhead), probably due to obstruction of the bronchus (plug formation) and resorption of air from the affected lobe, and a mild shift of the cardiac silhouette towards the right hemithorax. This is an example of obstructive resorption atelectasis, commonly seen in the right middle or cranial lobes in cats with bronchial disease.
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12.88 Caudal close-up of a DV thoracic radiograph of an English Springer Spaniel following thoracocentesis (causing subcutaneous emphysema) for a chronic pyothorax. There is an iatrogenic pneumothorax, which highlights the pleural surface of the left caudal lung lobe. The lung has lost its normal shape and is rounded with increased opacity and thickening of the pleura (arrowheads). There is cicatrization atelectasis due to the thickened pleura preventing re-expansion of the lung.
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12.89 Lateral thoracic radiograph of a 4-month-old German Shepherd Dog puppy with a patent ductus arteriosus and congestive heart failure. Note the typical perihilar distribution of the pulmonary oedema, and enlargement of the pulmonary veins and arteries and cardiac silhouette. (Courtesy of Cambridge Veterinary School). Lateral thoracic radiograph of a kitten with a patent ductus arteriosus and pulmonary oedema.
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12.90 Suspected pathophysiology of neurogenic pulmonary oedema.
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12.91 Pathophysiology of pulmonary oedema secondary to decreased interstitial tissue pressure.
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12.92 Lateral thoracic radiograph of a 4-year-old mixed breed dog with neurogenic pulmonary oedema, following electrocution due to biting an electrical cord. Notice the alveolar lung pattern in the caudodorsal lung fields, consistent with a non-cardiogenic form of pulmonary oedema. Lateral thoracic radiograph of a dog with a history of strangulation. There is increased opacity in the caudodorsal lung fields with an interstitial to alveolar pattern.
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12.93 Pathophysiology of near drowning.
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12.94 Lateral thoracic radiograph of a dog obtained 8 hours after a near drowning accident in a river. The dog was able to walk home and only became severely dyspnoeic several hours later. A diffuse patchy alveolar pattern and slight dyspnoea-related movement blur can be seen.
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12.95 Pathophysiology of smoke inhalation.
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12.96 Lateral thoracic radiograph of a 6-month-old German Shepherd Dog that was rescued from a fire. There is a patchy alveolar pattern, particularly in the caudodorsal lung fields, consistent with smoke inhalation.
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12.97 VD thoracic radiograph of a 6-year-old Bernese Mountain Dog obtained 1 day after a road traffic accident, resulting in multiple pelvic fractures and hindlimb injuries. The thorax is normal. A repeat radiograph obtained 4 days later. There is increased lung opacity, particularly in the left lung with a partial alveolar pattern. The dog had developed progressive systemic disease characterized by hyperthermia, immune-mediated haemolytic anaemia, erlichiosis, lymphadenopathy and metabolic acidosis. The dog was euthanized with a clinical diagnosis of ARDS.
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12.98 Lateral thoracic radiograph of a 5-year-old Domestic Shorthair cat with terminal chronic renal failure. There is increased opacity with a partial alveolar pattern in the caudal lung lobes, aortic (white arrowheads) and gastric rugal (black arrowhead) mineralization, and gas distension (dyspnoea). The cat was euthanized and necropsy confirmed chronic renal failure with extensive metastatic mineralization and uraemic pneumonitis.
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12.99 VD thoracic radiograph of an 8-year-old Irish Setter with sudden onset of dyspnoea. The left caudal lung lobe appears hyperlucent and less vascularized than normal. Close-up of the left caudal lung lobe. The lobar artery (between arrowheads) is distended and then disappears at the level of the ninth rib (*). These are classic, albeit rare, signs of pulmonary thromboembolism: a thrombus-distended pulmonary artery and tributary oligaemia.
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12.100 VD thoracic radiograph of a 6-year-old Domestic Shorthair cat with sudden onset of severe dyspnoea. There is increased opacity with a partial alveolar pattern in the left caudal lung lobe in the costodiaphragmatic recess. Thoracic high-resolution CT image at the level of the accessory lung lobe demonstrates a wedge-shaped peripheral consolidation in the left caudal lung lobe consistent with an infarct. Close-up of a pulmonary CT angiogram at the same level demonstrates contrast medium within the caudal vena cava (*) and aorta (A), and a large filling defect (dark core) in the left caudal lobar pulmonary artery (arrowhead), indicating an occlusive thrombus.
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12.101 Close-up of a VD thoracic radiograph of the right caudal lung lobe of a 1-year-old Domestic Shorthair cat, which had sustained sudden respiratory arrest when an intramedullary pin was advanced into the humerus for a fracture repair. The radiograph was obtained during the resuscitation attempts, which ultimately failed. There is increased lung opacity with an alveolar pattern in the right costodiaphragmatic recess. Microscopic examination of the lungs confirmed a massive shower of occlusive fat emboli (red stained) throughout the pulmonary capillary bed and pulmonary fat embolism was established as the cause of death. Oil Red O with Mayer’s haemulum stain; original magnification x220. (Reproduced from with permission from the )
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12.102 Caudal close-up of a lateral thoracic radiograph of a 4-year-old Labrador Retriever with a patent ductus arteriosus and left-to-right shunt, obtained during a coil embolization procedure. Three metallic coils can be seen dislodged in the caudal lung lobe arteries. Coils designed for human infants are commonly used in dogs, which typically have a wider duct. Due to the well developed collateral circulation, dislodged coils are usually of no clinical consequence. The duct was eventually successfully occluded.
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12.103 Thoracic high-resolution CT image at the level of the accessory lung lobe of an 8-year-old Hungarian Vizsla with pyrexia and carcinomatous infiltrate in a peripheral lymph node. A frond-like subpleural infiltrate is present in the dorsal aspect of both caudal lung lobes. Microscopic examination of a corresponding lung area reveals a matching neoplastic capillary and interstitial subpleural infiltrate. Final diagnosis on necropsy was an adrenal carcinoma and pulmonary carcinosis. H&E stain; original magnification x160. (Reproduced from with permission from the )
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12.104 Lateral thoracic radiograph of a Labrador Retriever with coagulopathy due to warfarin toxicity. Note the tracheal narrowing, pleural fluid and partial alveolar lung pattern. This combination is highly suggestive of coumarin toxicity. (Courtesy of Cambridge Veterinary School)
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12.105 Pathophysiology of blunt external thoracic trauma.
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12.106 DV thoracic radiograph of a Chihuahua following thoracic trauma. There are multiple right rib fractures. The right lung is consolidated and causes a cardiac shift towards the left. Lung contusion is usually adjacent to the site of blunt impact. (Courtesy of Cambridge Veterinary School)
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12.107 A close-up of a lateral thoracic radiograph of a 10-year-old Labrador Retriever with pulmonary alveolar microlithiasis. The dog had harsh lung sounds but otherwise no cardiorespiratory abnormalities. Notice the widespread micronodular mineralization, which is most pronounced in the perihilar region. Postmortem radiograph of the right lung. The lung was solidly mineralized and had to be sectioned with a saw. The reason for euthanasia in this dog was severe chronic coxofemoral and cubital arthritis not cardiorespiratory disease. (Reproduced from with permission from the )
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12.108 Lateral thoracic radiograph of a 1-year-old English Springer Spaniel with bronchopneumonia. Typical radiographic features include patchy areas of alveolar pattern and peribronchial infiltrate throughout the lungs. (Courtesy of Cambridge Veterinary School)
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12.109 VD thoracic radiograph of a 6-year-old Briard with lobar pneumonia of the right middle lung lobe. There is an alveolar lung pattern with air bronchograms of the entire lobe with clear margination to neighbouring lobes (lobar sign). The heart is partially obliterated by the lobe (border obliteration sign) and mainly contained within the right hemithorax (cardiac shift), indicating a degree of collapse of the right middle lung lobe. Right lateral thoracic radiograph. Due to the hypostatic collapse of the entire right lung, the opacification of the middle lobe is not distinguishable. Left lateral thoracic radiograph. The now non-dependent right lung is fully aerated again, except for the middle lobe which is now visibly opacified. This is an indication of alveolar disease rather than just hypostatic lung collapse. Notice the DV orientation of the right middle bronchus, facilitating preferential aspiration in this lobe. The radiopaque marker in the trachea should be ignored as it was placed for an interventional procedure.
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12.110 Lateral thoracic radiograph of a dog with bronchiectasis and associated bronchopneumonia. Notice the numerous widened, irregular, thick-walled bronchial ring shadows surrounded by lung tissue of increased opacity. The oesophagus is distended with gas.
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12.111 Dorsal plane thoracic ultrasound image of a 5-year-old Staffordshire Bull Terrier with pneumonia. The visible right caudal lung lobe is echogenic and contains two anechoic tubular structures, representing a pulmonary artery (black arrowhead, confirmed with Doppler ultrasonography) and a fluid-filled bronchus with hyperechoic walls (mineralized cartilage, white arrowheads). This is called a and is useful in the differentiation of altered lung tissue from masses or herniated abdominal organs (liver).
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12.112 High-resolution thoracic CT image at the level cranial to the aortic arch of a 12-year-old Miniature Dachshund with severe respiratory distress of unclear aetiology after clinical and radiographic work-up. There is partial consolidation of the right cranial lung lobe with a ventral distribution, consistent with pneumonia. The dog improved after antibiotic treatment.
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12.113 Lateral thoracic radiograph of a cat with polyarthritis. There are multiple ill defined areas of focal alveolar disease with a nodular appearance in places. Based on the clinical signs and radiographic changes, a granulomatous lung disease was suspected but neoplasia and pneumonia were differential diagnoses. A bronchoalveolar lavage showed chronic inflammatory changes. The lesions resolved following antibiotic therapy.
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12.114 Lateral thoracic radiograph of a 9-year-old Labrador Retriever obtained after a barium oesophagram had been performed. The oesophagus is normal, but barium was aspirated in the right middle and left caudal lung lobes. Lateral thoracic radiograph of a German Shepherd Dog with severe aspiration pneumonia. Note the typical cranial and ventral distribution of alveolar opacity with air bronchograms. Lateral thoracic radiograph of a Shih-Tzu with aspiration pneumonia and megaoesophagus. Note the generalized dilatation of the oesophagus (between white arrowheads) and ventral deviation of the trachea (black arrowhead). There are multifocal areas with an alveolar pattern within the dependent lobes, most marked in the right middle lobe.
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12.115 Caudodorsal close-up of a lateral thoracic radiograph of a dog with leptospiral pneumonia. There is a mild increase in lung opacity with a fine-structured interstitial pattern, typical of mild or early-phase leptospirosis.
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12.116 Lateral thoracic radiograph of a 9-year-old mixed breed dog with mycoplasmal pneumonia. There is a diffuse bronchointerstitial lung pattern throughout the lungs.
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12.117 Lateral thoracic radiograph of a 7-month-old Chihuahua with canine distemper virus infection. There is a diffuse increase in lung opacity with an interstitial pattern, more pronounced caudodorsally. This feature is representative of an early viral stage of pneumonia. Bacterial secondary infection will add a patchy alveolar pattern with a random or ventral distribution. (Courtesy of the University of California Davis)
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12.118 Major endemic areas for blastomycosis, coccidioidomycosis and histoplasmosis in the USA. (Reproduced from with permission from the publisher)
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12.119 Lateral thoracic radiograph of a dog with chronic inactive histoplasmosis. There are numerous small mineralized nodules throughout the lung (calcified granulomas). The left tracheobronchial lymph node (dorsal to the carina) is moderately enlarged and also mineralized.
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12.120 Lateral thoracic radiograph of a 3-year-old Golden Retriever with active pulmonary blastomycosis. There is alveolar disease cranioventrally and caudodorsally, numerous 2–4 mm soft tissue nodules throughout the lung, and a mild dorsal deviation of the caudal trachea and an associated soft tissue opacity (*) suggestive of mediastinal lymphadenopathy. (Courtesy of the University of California Davis) Lateral thoracic radiograph of a dog with active diffuse pulmonary blastomycosis. There is a miliary pattern throughout the lungs created by many small soft tissue nodules. Corresponding necropsy image with multiple small pulmonary granulomas. (Courtesy of the University of Pennsylvania)
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12.121 Lateral thoracic radiograph of a 2-year-old Rottweiler with pulmonary coccidioidomycosis. There is a diffuse pattern of poorly circumscribed nodules throughout the lungs and perihilar lymphadenopathy, causing caudal tracheal deviation. Postmortem image of a lung section demonstrates disseminated fungal granulomas. (Courtesy of the University of California Davis)
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12.122 Lateral thoracic radiograph of a 10-year-old Domestic Shorthair cat with pulmonary cryptococcosis. There is a large caudodorsal soft tissue mass (granuloma) and marked perihilar lymphadenopathy, causing tracheal deviation. (Courtesy of the University of California Davis)
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12.123 Lateral thoracic radiograph of a 1-year-old Cavalier King Charles Spaniel with infection. There is a generalized interstitial pattern with mild bronchial thickening. The generalized nature of the changes in a young dog is unusual but in combination with the breed is highly suggestive of pneumocystosis.
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12.124 Right lateral thoracic radiograph of a 10-year-old Domestic Shorthair cat with pulmonary toxoplasmosis. There are patchy areas of alveolar lung pattern in the mid-ventral lung fields. The opposite lateral film also revealed right middle lung lobe collapse.
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12.125 Lateral thoracic radiograph of a dog with dirofilariosis. There is a widespread increase in lung opacity, caused by enlarged, tortuous pulmonary arteries, and oedematous and granulomatous reactive lung.
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12.126 Lateral thoracic radiograph of a Staffordshire Bull Terrier with infection. Note the peripheral distribution of the pulmonary lesions (arrowed), which is commonly seen in angiostrongyloidosis.
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12.127 Lateral thoracic radiograph of a 7-month-old Domestic Shorthair cat with an infection in the small airways. There is a bronchointerstitial infiltrate with peribronchial thickening throughout the lungs. Caudodorsal close-up of a lateral radiograph of a 2-year-old Cavalier King Charles Spaniel with a infection. There is a bronchointerstitial lung pattern with marked bronchial thickening.
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12.128 Caudodorsal close-up of a lateral thoracic radiograph of a 2-year-old Boxer with PIE. There is a bronchointerstitial lung pattern with bronchial mineralization and thickening, and small areas of peribronchial infiltrate (arrowheads). Lateral thoracic radiograph of a 2-year-old Boxer with chronic coughing and eosinophilia. There is a bronchointerstitial pattern with mineralized and thickened bronchi throughout the lungs, and two ovoid soft tissue nodules (one is visible on this view, arrowhead). The differential diagnoses includes PIE with lung granulomas, as well as neoplastic and fungal disease.
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12.129 Lateral thoracic radiograph of a 6-month-old Afghan Hound that developed acute dyspnoea after being doused in chlorinated carpet cleaner. There is a diffuse interstitial to alveolar pattern throughout the lungs. The preferential caudodorsal distribution is a hallmark of inhalation pneumonitis.
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12.130 Lateral thoracic radiograph of a cat with exogenous lipid pneumonia. The cat had been medicated with liquid paraffin for constipation. Note the right middle lung lobe collapse, caudodorsal alveolar opacity and bronchiectasis, and cavitating lesions throughout the ventral lungs. The generalized interstitial pattern could be related to lipid transport without removal by pulmonary macrophages.
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12.131 Lateral thoracic radiograph of a 12-year-old Domestic Shorthair cat with a bronchoalveolar carcinoma. There is a mixed bronchoalveolar pattern and bronchiectasis present throughout all lung lobes. DV thoracic radiograph of a 10-year-old Domestic Shorthair cat with a bronchoalveolar carcinoma. There is a generalized bronchointerstitial pattern throughout the lungs and a cavitated mass in the left caudal lobe. (Courtesy of E. Ballegeer)
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12.132 DV thoracic radiograph of a cat with a pulmonary carcinoma. The left caudal lung lobe has a soft tissue opacity and is partially collapsed (cardiac and diaphragmatic shift, arrowed). This is most likely to be the result of bronchial obstruction and peripheral resorption atelectasis.
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12.133 DV thoracic radiograph of a cat with unilateral pleural effusion. There is preferential collapse of the left cranial lung lobe with accumulation of fluid around the collapsed lobe (arrowed). This is suggestive of pathology within the left cranial lobe. Ultrasound-guided fine-needle aspiration of the affected lung confirmed lymphoma.
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12.134 Lateral thoracic radiograph of a cat with hypertrophic cardiomyopathy and cardiogenic interstitial pulmonary oedema. There is cardiomegaly, pulmonary vascular distension, a small amount of pleural effusion and a diffuse interstitial pattern throughout the lungs, most pronounced in the perihilar region. Repeat radiograph 12 hours after initiation of diuretic treatment reveals persistent cardiomegaly, normal sized pulmonary vessels, resolution of the pleural effusion and lung opacification. Prompt resolution of radiographic signs after diuresis is a hallmark of cardiogenic pulmonary oedema.
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12.135 Lateral thoracic radiograph of a kitten with acute interstitial pneumonia secondary to feline leukaemia virus infection. The fine vascular structures are blurred yet still visible, and there is an overall increase in lung opacity. Acute viral pneumonia typically presents with radiographically normal lungs or an interstitial lung pattern, as in this case.
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12.136 Caudodorsal close-up of a lateral thoracic radiograph of a 5-year-old German Shepherd Dog with marked dyspnoea. There is a fine-structured interstitial pattern throughout the caudodorsal lung fields. The histological diagnosis was pulmonary fibrosis of unknown aetiology.
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12.137 Lateral thoracic radiograph of a 14-year-old West Highland White Terrier with idiopathic pulmonary fibrosis. Notice the general increase in lung opacity with an interstitial pattern, partial tracheal collapse and dyspnoea-related gas distension of the stomach (aerophagia). There is mild right cardiac and marked hepatic (not included in image) enlargement, features commonly seen in terrier breed dogs with idiopathic pulmonary fibrosis.
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12.138 High-resolution lung CT image at the level of the caudal thorax of a 12-year-old West Highland White Terrier with idiopathic pulmonary fibrosis. There is a mild generalized increase in lung opacity (ground-glass opacity) and a small subpleural fibrotic infiltrate in the right caudal lung lobe. The oesophagus is mildly distended with gas. On a slightly more cranial image, there is a hyperattenuating infiltrate in the dorsal portions of both caudal lung lobes and subpleural bands. Patches of ground-glass attenuation are present in the right lung. These changes are consistent with fibrosis.
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12.139 High-resolution lung CT image at the level of the caudal thorax of an 11-year-old obese Domestic Shorthair cat with fibrotic lung changes. Notice the ground-glass opacity of the lung, a small subpleural consolidation (curved arrow) and bands of soft tissue originating from the pleural surface (straight arrow).
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12.140 Lateral port film of a 9-year-old Domestic Longhair cat for radiation treatment planning with cobalt photons for a non-resectable interscapular fibrosarcoma. The beam field includes the very dorsal aspect of the caudal lung fields. Lateral thoracic radiograph obtained 1 month after completion of radiation therapy demonstrates a sharply delineated alveolar opacity of the exposed lung, consistent with acute radiation pneumonitis. Caudodorsal close-up of a lateral thoracic radiograph obtained 6 months following radiation. The affected area is now slightly reduced in size and of a mixed interstitial–alveolar pattern. These findings are consistent with radiation-induced chronic lung fibrosis and will remain permanent. (Courtesy of D. Thrall)
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12.141 VD thoracic radiograph of a dog with systemic lymphosarcoma and a diffuse fine-structured interstitial infiltrate. High-resolution CT image at the level caudal to the carina demonstrating a diffuse ground-glass opacity throughout the lungs.
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12.142 Left caudal close-up of a VD thoracic radiograph of a 5-year-old Irish Setter with heartworm disease and an associated calcified pulmonary haematoma. Notice the distended left lobar artery (A) and the eggshell-like mineralization of the haematoma. Caudodorsal close-up of a lateral thoracic radiograph of a 5-year-old Dachshund with Cushing’s disease. Diffuse interstitial and bronchial mineralization has resulted in a bronchointerstitial pattern. The bronchi and pulmonary parenchyma have a subtle mineral opacity. In most cases, interstitial mineralization is not marked enough to cause a mineral radiopacity, and the interstitial opacity is often mistaken for interstitial oedema. A persistent interstitial lung pattern, despite diuretic treatment in hyperadrenocorticoid dogs, should prompt consideration of mineralization and fibrosis as differential diagnoses.
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12.143 Dorsal thoracic scintigram of a dog obtained approximately 2 hours after intravenous injection of a bone-binding diphosphonate compound. Notice the diffuse radiopharmaceutical uptake in the lungs compared with the photopenic abdomen. Differential diagnoses for this uptake include Cushing’s disease, heterotopic bone formation, diffuse pulmonary metastases and recently performed lung scintigraphy.

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