Small Animal Radiology and Ultrasound: A Diagnostic Atlas and Text

Chapter Two The Thorax 31
Fig. 2-7 A 2-year-old male Labrador
Retriever with an acute onset of
vomiting, nystagmus, and ataxia. A,
In the initial lateral thoracic radiograph
the increased density of the
thorax is the result of underexposure.
B, A second lateral thoracic radiograph
was obtained using the proper
radiographic technique. The pulmonary
structures and airways are
defined much more clearly in the second
radiograph. Underexposure of
the radiograph can mimic a pulmonary
infiltrate. Diagnosis: Normal
thorax.
A
B
important, because exposures of 1/30 second or less are essential in order to minimize respiratory
motion. Longer exposure times may result in apparent motion, causing blurring
of pulmonary vessels, bronchi, interstitial structures, and overlying bony structures. This
can create the appearance of a pulmonary infiltrate or obscure pulmonary lesions. If
motion is suspected, the bony structures should be evaluated closely, because loss of definition
of ribs or bony structures is readily detectable.