Why Is This Animal Coughing?

Introduction
Coughing is a common presenting sign in both dogs and cats. there are many causes of coughing involving the respiratory tract, and radiographs are a good survey diagnostic test to further evaluate which part of the respiratory tract is involved. the airways are normally a primary or secondary location of disease, and we will focus on imaging these structures.

Radiographic technique
A complete evaluation includes a lateral neck and three thoracic projections; left lateral recumbency, right lateral recumbency, and either a ventrodorsal or dorsoventral projec- tion. the lung on the dependent side on a lateral projection is significantly hypoinflated compared to the opposite side, and will not provide enough contrast to be able to see structures clearly. therefore, on a right lateral recumbent radiograph, the majority of the structures seen will be in the well-inflated left lung.

Airway collapse
The trachea and airways can be affected by many types of disorders that cause cough- ing. one of the more common degenerative diseases is tracheal and bronchial collapse, which affects the compliance of the cartilage in the airways. the collapse of the airways creates a mechanical obstruction resulting in cough, and inflammatory change may also be present contributing to the symptoms. toy and small breed dogs are predis- posed to this condition.

Dogs can be affected by lower airway collapse alone, or in conjunction with tracheal collapse. fluoroscopy can be used to advantage for a definitive diagnosis, as it is a real time imaging method. radiographs are often not accurate in diagnosing the true loca- tion of airway collapse or the extent, and are not recommended for final diagnosis of airway collapse. [...]