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CHAPTER 20 III The Torso 223

Figure 20-22 • Close-up view of the thoracic region of a great horned owl (ventral perspective, keel and associated muscles removed)
showing the cranial aspect of the heart at the top with the caudal aspect directly below, partially obscured by the surrounding liver.

result in asymmetrical enlargement and displacement or no doubt exists as to the presence of hepatomegaly
within the celomic cavity, the likelihood of obtaining (Figure 20-24).
closely comparable lateral and VD views of the cardiac Diminished liver size in wild birds is far more
silhouette is quite small. common than hepatomegaly and in most instances
There is no predictable or consistent advantage yet results from starvation brought about by some sort of
identified to making right and left lateral views in debilitating injury, particularly to the wing, forcing

birds with suspected lung disease. Theoretically speak- these birds to become ground dwellers (Figure 20-25).
ing, the larger the bird and the more lateralized the Small cage birds, such as canaries and budgies, that
disease, the greater the likelihood that alternate side suffer from chronic disease-related inappetence may
radiography would reveal a difference, which in turn also show varying degrees of radiographically detect-
might enable one to determine the side that was dis- able liver shrinkage.
eased. My sense is that the VD view, even with its
acknowledged limitations, would likely serve the same
purpose but with a greater degree of confi dence, much Spleen and Pancreas
as with pets like dogs and cats.
The spleen is a small, rather nondescript organ located
near the stomach (ventriculus-proventriculus). It is
Liver
highly variable in shape, ranging from circular to oval
The liver is the lower half of the central visceral silhou- to elongate, depending on the species. Its principal
ette, which loosely resembles that of an hourglass functions are to remove aged or damaged red cells
when projected ventrodorsally, albeit a highly variable from the circulation and to aid in the production of
one. As mentioned previously, the presence of an lymphocytes and antibodies. The spleen of birds does
asymmetrical central visceral silhouette has yet to not serve as a blood reservoir as in mammals. The
establish itself as a reliable indicator of either cardiac or spleen is rarely injured and only occasionally enlarged
hepatic disease (Figure 20-23). If this is the case, it must to the extent that its altered appearance can be appreci-
be acknowledged that there are instances where little ated radiographically. A healthy pancreas cannot be

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