P. 568

An Urban Experience
thoracic radiographs. Pulmonary metastases result in numerous variable size and usually round pulmonary nodules. Round cell neoplasia (lymphoma, histiocytic sarcoma) have a variable radiographic appearance ranging from unstructured interstitial patterns over pulmonary nodules and masses to diffuse in ltrates. Concurrent thoracic lymphadenopathy is common.
Airway associated neoplasia (e.g., originating from pharynx, larynx or trachea) is relatively uncommon but usually readily identi ed as focal alteration of the normal air- lled lumen of the airway by a wall associated mass. Other mass lesions associated with the neck or thorax (e.g., thyroid carcinoma, heart base mass or oesophageal mass) can result in airway irritation and cough.
Traumatic and physical causes:
Tracheal and/or mainstem bronchial collapse
is common in small breed dogs. If severe it may be visible on survey radiographs. In other cases dynamic imaging (radiographs or  uoroscopy during inspiration, expiration and during cough) may be needed for diagnosis. Hypoplastic trachea is a congenital condition and is most commonly seen in bulldogs. Affected animals are presented at a young age and
have generalized narrowing of the trachea on survey radiographs. Concurrent aspiration pneumonia is common. Inhaled foreign bodies are usually easily detected as they contrast with the normal air- lled
lumen of the trachea or bronchi. Inhalation of irritating gases, liquids or solids causes variable radiographic changes ranging from normal to severe caudodorsal unstructured interstitial to alveolar patterns indicative of noncardiogenic pulmonary oedema. The intrathoracic trachea is well protected from trauma, however, trauma to the neck is common (e.g., bite would or excessive pull on leash) and may result in tracheal irritation and cough. If a perforating wound to the trachea has occurred, gas inclusions within cervical soft tissues, pneumomediastinum and subcutaneous emphysema will be evident radiographically. Similar to an oesophageal neoplasm, oesophageal enlargement for other reasons (megaoesophagus, oesophageal foreign body) may also result in cough.
Cardiovascular causes:
In addition to heartworm disease and heart base masses listed above, many heart diseases have the potential
to result in cough either by physical compression of the caudal trachea and mainstem bronchi by an enlarged cardiac chamber (such as seen with left atrial enlargement in dogs with mitral endocardiosis
and regurgitation) and/or secondary to congestive left heart failure resulting in cardiogenic pulmonary oedema. Radiographically, cardiomegaly is recognized by enlargement of one or more of the cardiac chambers.
In case of left atrial enlargement which commonly results in cough in canine patients, the caudal margin of the cardiac silhouette is straight, there is loss of the caudal cardiac waist, the trachea is displaced dorsally, and
on the VD or DV view there is widening of the tracheal bifurcation (“bow legged cowboy sign”). In congestive left heart failure most dogs exhibit a caudal dorsal distributed (perihilar) unstructured interstitial to alveolar pattern and possibly visible enlargement of the pulmonary veins compared to the corresponding pulmonary arteries.
In Doberman Pinschers with dilated cardiomyopathy and resultant congestive heart failure and in dogs with acute rupture of the chordae tendineae, distribution of pulmonary oedema is often random rather than con ned to the caudal dorsal lung  elds.
1. Thrall DE. Textbook of Veterinary Diagnostic Radiology. 6th ed. St. Louis: Elsevier Saunders; 2013.
2. Ettinger SJ. Coughing. Chapter 46. In: Textbook of Veterinary Internal Medicine. In: Ettinger SJ, Feldman EC, editors. 5th ed. Philadelphia: WB Saunders Co; 2000.
3. Suter PF. Thoracic Radiography. Wettswil: Selbstverlag PF Suter; 1984.

   566   567   568   569   570