Small Animal Radiology and Ultrasound: A Diagnostic Atlas and Text

Chapter Three The Abd omen 315
Fig. 3-79 A 12-year-old neutered
female Dachshund with acute
abdominal distention. The lateral
view revealed that the stomach is
severely distended with food and gas.
Differential diagnoses include gastric
distention from overeating, gastric
outflow obstruction, or gastric distention
with volvulus. There is no
segmentation of the stomach or displacement
of the pylorus from its
normal position. Diagnosis: Acute
gastric distention.
Only a few morphology-distorting diseases that affect the stomach are not recognizable
on survey radiographs, especially if the stomach contains air or if air is administered to
the patient by stomach tube. Most radiographic changes seen with these diseases affect
either the mucosa or wall of the stomach, and these structures can be delineated by air. If
a portion of the stomach is difficult to evaluate due to the presence of normal gastric fluid,
positional maneuvers, which take advantage of the gravitational effect on air and fluid, can
be used to define that portion of the stomach. Gastric masses, such as tumor, granuloma,
or gastrogastric intussusception, may be identified on noncontrast radiographs when air is
present within the stomach. 328 Using both right and left lateral, sternal, and dorsal recumbent
radiographs, air within the stomach can be manipulated to define all areas of the
stomach. This will often allow for a diagnosis to be made and saves the cost and stress of a
GI series. As with a contrast study, it is important to identify the lesion on multiple radiographs
in order to be confident that the abnormality observed is not merely an artifact.
Infiltrative lesions of the gastric wall, such as tumors or granulomas, may interfere with
normal gastric distention and may alter the shape of the stomach. Although shape alteration
is usually the result of gastric wall lesions, incarceration of the stomach by the omentum
can also alter the stomach’s shape because it will interfere with gastric distention.
Some of these diseases may only be identified using either the GI series or double-contrast
gastrogram. Some gastric diseases, such as nonulcerative gastritis, rarely have recognizable
changes even on contrast gastrography, and confirmation of the diagnosis requires
endoscopy or biopsy.
Gastrointestinal Series. For complete evaluation of the stomach during the GI series, ventrodorsal,
dorsoventral, and right and left lateral radiographs should be taken initially, and
at least a ventrodorsal or dorsoventral and a lateral view (choice of which depends upon
the area most suspected of harboring pathology) should be taken thereafter as the study
progresses (Fig. 3-82). The choice of which views to take (right versus left lateral, dorsoventral
versus ventrodorsal) may be determined by which position the animal is most comfortable
in or by which view shows a suspicious abnormality. It is very important that
multiple views be taken during the study, because the most important diagnostic criterion
is the repeatability of a lesion.