Page 344 - Feline diagnostic imaging

352 22 Gastrointestinal Disease

(b)

(a)

Figure 22.5 Megaesophagus in a 4-year-old domestic longhair with a history of chronic vomiting. The esophagus is greatly dilated
and mostly filled with air. Some fluid opacity is seen in the distal thoracic esophagus. Esophagitis was seen on postmortem but the
cause of megaesophagus was not identified. (a) Lateral projection. (b) Ventrodorsal projection. Arrows indicate the margins of the
esophagus.

allow the sonographer to determine their shape. Some right lateral recumbent view is most helpful. A normally
balls appear as a homogeneous, circular echoic structure; positioned pyloric antrum should be ventral and fluid filled
others are hyperechoic and circular but have an anechoic even when the stomach is dilated but the pylorus will be
center. displaced dorsally and cranially in cases of GDV. The stom-
Foreign material can rarely migrate through the intesti- ach may have a compartmentalized appearance in some
nal wall. In an unusual case, a midabdominal mass cases. The pylorus is not always obvious when fluid filled.
was seen displacing the intestines caudally on radiogra-
phy. Ultrasound revealed that the mass contained fluid 22.3.3 Gastric Neoplasia
pockets, which were aspirated. Cytology was consist-
ent with pyogranulomatous inflammation. Subsequent Lymphoma [17,18] is the most common type of neoplasia
surgery revealed filamentous bacteria believed to be but other neoplasms include adenocarcinoma and leio-
Actinomyces [14]. myosarcoma. On survey radiography (Figure 22.7), thick-
ening of the gastric wall may cause the wall to be rigid so
that instead of a normal smooth, circular gas bubble, a
22.3.2 Gastric Dilation with Volvulus distorted or malpositioned gas bubble is seen. In a few
and Dilation
cases, gas may outline a mass protruding into the lumen.
Gastric dilation with volvulus (GDV) is uncommon in cats Occasionally, mineral in the mass may cause a mass to be
but has been reported [15,16]. In a report of 10 cats, five had visible. Masses in the area of the pylorus can cause out-
volvulus and five had dilation alone [15]. Three of the cats flow obstruction, resulting in gastric distension. Large
were also diagnosed with a diaphragmatic hernia. Another masses may be difficult to differentiate from a full stomach
study further suggested that diaphragmatic hernia could or liver mass.
predispose to gastric dilation [16]. On radiography, the On an upper GI series, key signs are rigidity and/or
stomach is distended in both GDV and dilation alone. Both thickening of the gastric wall or irregularity of the barium
lateral views should be exposed for comparison but the contrast column. A filling defect may be present if a gastric