Page 567 - ONLINE PROCEEDING BOOK WSAVA 2017
P. 567

WSVA7-0304
DIAGNOSTIC IMAGING II
IMAGING THE COUGHING DOG
S. Hecht1
1University of Tennessee, Small Animal Clinical Sciences, Knoxville, USA
IMAGING THE COUGHING DOG
Silke Hecht, Dr. med. vet., Diplomate ACVR, Diplomate ECVDI
Professor in Radiology
C247 Veterinary Medical Center, University of Tennessee College of Veterinary Medicine, Knoxville, TN 37996, USA
shecht@utk.edu
Introduction (1):
Coughing is one of the most common presenting complaints for dogs in small animal practice. A plethora of disorders of the respiratory tract but also of other thoracic structures can result in cough. Although computed tomography is gaining popularity in veterinary medicine, cervical and thoracic radiographs remain a mainstay in the diagnostic workup of these patients.
A lateral view of the neck is usually most helpful for evaluation of pharynx, larynx and trachea. However, even though these structures are superimposed over the cervical spine and dif cult to evaluate on a VD view, a VD view should also be obtained to allow full evaluation of the cervical soft tissues. The radiographic series of a thorax should consist of a right lateral, a left lateral and a VD or DV view. Acquisition of both the right and left lateral view is paramount as lateral recumbency quickly results in atelectasis of the dependent lung
lobes which may obscure pulmonary in ltrates, nodules or mass lesions. In some instances acquisition of both
a VD and DV view may be indicated as the VD view allows improved assessment of the thoracic structures in case of pleural effusion and easier evaluation of
the cardiac silhouette, while the DV view results in improved visualization of the caudal dorsal lung  elds. A radiographic diagnosis in a dog presented with cough can be challenging as some diseases especially in the early stage may not result in radiographic abnormalities, physiologic variations or aging changes may mimic pathologic lesions and result in an erroneous diagnosis, concurrent problems may be present all of which could be responsible for the clinical signs, and as imaging  ndings in some thoracic (especially pulmonary) diseases overlap. A systematic approach to the thoracic radiograph should include assessment of the thoracic wall, diaphragm, mediastinal structures, pleural space, cardiovascular system and lung.
Causes of coughing and imaging  ndings (1-3): In ammatory, parasitic and allergic conditions:
Pharyngitis and tonsillitis do usually not result in signi cant radiographic abnormalities although severe in ammation may result in noticeable soft tissue swelling of laryngeal and pharyngeal structures on radiographs. Similarly, radiographs in dogs with tracheitis are
often unremarkable or may show diffuse tracheal narrowing in severe cases. Lower airway disease (infectious bronchitis, asthma and pulmonary parasites) is often characterized by a diffuse mixed bronchial
and unstructured interstitial pulmonary pattern with diffuse increased opacity to the lung with thickened
and sometimes irregularly shaped bronchial walls. In extreme and chronic cases, irreversible and irregular widening of bronchi may occur (bronchiectasis). Bacterial pneumonia (bronchopneumonia or aspiration pneumonia) typically results in a cranial ventrally distributed alveolar pattern which may be unilateral or bilateral and is characterized by increased opacity of the affected lung lobe(s) with complete loss of visualization of the pulmonary vascular margins. If bronchi within these lung lobes remain air- lled, air bronchograms will be visible. An abnormal lung lobe bordering normal air- lled lung will result in a lobar margination sign. Pulmonary abscessation is rare but may occur for instance following aspiration of a foreign body. A pulmonary abscess usually appears as a round or oval variable size soft tissue opacity pulmonary mass which may contain gas opacity foci. Viral pneumonia may not result in radiographic abnormalities or may manifest as a diffuse unstructured interstitial pattern. Fungal disease has a variable appearance on radiographs and may be associated with an unstructured interstitial pattern, multiple pulmonary nodules, masses, or irregular in ltrates. Intrathoracic lymphadenopathy, especially tracheobronchial lymphadenopathy, is common. Heartworm disease primarily results in cardiovascular changes (enlargement of the main pulmonary artery segment, right heart enlargement, dilation, blunting and tortuosity of pulmonary arteries) but is also often associated with concurrent mixed pulmonary patterns indicative of eosinophilic bronchopneumopathy.
Neoplasia:
Even advanced pulmonary neoplasia may not be associated with clinical signs. However, both primary pulmonary neoplasms (e.g., adenocarcinoma) and metastatic disease can result in cough. A primary pulmonary neoplasm is characterized by a variable size usually sharply marginated mass. The lesion is most commonly homogeneously soft tissue opaque but may be cavitary. Primary lung tumours do not usually result
in visibly enlarged tracheobronchial lymph nodes on
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