Small Animal Radiology and Ultrasound: A Diagnostic Atlas and Text

Chapter Three The Abd omen 313
preparations), and electrolyte status on the various alimentary organs are necessary to
optimize alimentary interpretation at the survey radiographic level.
S T O M AC H
Density Changes. Gastric lesions may be recognizable on survey radiographs providing the
stomach is filled with air and does not contain a large amount of food. Foreign bodies and
masses may protrude into the lumen and may be apparent. Because of this air-to-mass interface,
these tissue-dense lesions will have very discrete borders (Fig. 3-76). If a foreign body is
metal dense, the possibility of lead or zinc should be considered. This is particularly important
in the stomach, because gastric acid may solubilize lead and zinc and cause metal intoxication.
Zinc toxicity has been associated with ingestion of nuts, bolts, zinc-containing
ointments, and pennies minted after 1982. 327 Food in the stomach may disguise foreign matter.
If food or granular material is present in the stomach of an animal that has a history of
total anorexia or vomiting multiple times, this density most likely represents a foreign body.
Repeat radiographs taken after a fast of 18 to 24 hours may make it clear if the material is
indigestible. Food in the stomach, particularly if surrounded by air, may mimic foreign bodies.
Some foreign bodies may appear radiolucent if they are of a fat-dense material, like some
rubber balls, or have air-filled centers, such as seeds, nuts, or pits, and are surrounded by gastric
or intestinal fluid (Fig.3-77). Mineralization of the submucosa, appearing as a fine linear
calcification parallel to the mucosal border, may be seen with chronic renal failure (Fig. 3-78).
Size, Shape, or Position Changes. Changes in the size of the stomach may also be an
important sign of dysfunction. Although it is normally a distensible organ, the caudal
border of the stomach should not extend beyond the level of L4. Severe distention of the
stomach may be due to excess gas, food, or fluid within the stomach. Occasionally a dog,
particularly a young one, will simply overeat and the resultant gastric dilation will cause
clinical signs (Fig. 3-79). Gastric dilation in an anorectic or vomiting dog may indicate
some form of pyloric outflow obstruction or gastric dilation or volvulus. Gastric volvulus
is rotation of the stomach around its long axis. The degree of rotation may vary from
as little as 90 to 360 degrees or more. The most common is a 180-degree rotation. The
degree of gastric dilation will vary (Figs. 3-80 and 3-81). The classic appearance on a
Fig. 3-76 A 6-year-old male Great
Dane with weight loss for 3 months
and vomiting and diarrhea for 3
days. There are large, irregular tissue-dense
masses outlined by air in
the stomach (black g). The caudal
lung lobes revealed a nodular interstitial
pattern infiltrate. Differential
diagnoses include neoplasia or granuloma.
Diagnosis: Tuberculosis with
gastric, hepatic, and pulmonary
involvement.