Page 349 - Feline diagnostic imaging

22.4 Small ntestinal Disorders 357
22.3.7 Gastroduodenal Ulceration obstruction of the bowel. Initially, motility may be
increased but can decrease when obstruction persists. In
Gastroduodenal ulceration is uncommon in cats compared some cases, a dilated loop may signal disease in adjacent
to dogs with most but not all cases being the result of neo- bowel (a “sentinel” loop). For example, persistent gas in
plasia (Figure 22.10). Cats with gastric ulcers often present the duodenum can occur when there is peritonitis second-
with severe anemia secondary to gastroduodenal hemor- ary to pancreatitis.
rhage. Other clinical signs include anorexia, weight loss, On survey radiography, gas‐ or fluid‐filled loops of
and vomiting. Radiographs and ultrasonography are fre- small intestine should not exceed about 12 mm or twice
quently unremarkable but sonographic signs consistent the height of the midportion of the body of L2 [27]. In a
with ulceration that have been reported in dogs include study associating radiographic findings with feline intes-
thickening or loss of wall layering, visible mural defect, tinal disorders [28], dorsoventral measurements of the
accumulation of fluid in the gastric lumen, and decreased cranial endplate of L2 were made using the lateral projec-
motility [22]. Mesenteric lymph nodes may also be tion. Obstruction was more likely than other disease in
enlarged. A loss of serosal detail, especially if free gas is cats with a small intestinal diameter greater than twice
noted, indicates possible perforation [23]. In a study of that of cranial L2. The likelihood of no gastrointestinal
eight cats with gastroduodenal ulcers [23], seven had disease was less than 4% when the small intestinal diam-
sonography. Of these, only the three cats with neoplasia eter was greater than 2.5 times cranial L2. The probability
had sonographic findings similar to those seen in dogs with of mechanical obstruction was more than 70% when the
ulceration. Neoplasms diagnosed in this study included ratio was more than 3.
gastrinoma, ductal carcinoma that probably originated Dilation can be localized or generalized and mild to
from the pancreas, lymphoma, and adenocarcinoma. severe. Severe dilation is more common with obstruction
When the authors of the study reviewed the literature, the (e.g., foreign body, volvulus) as functional ileus tends to
most common neoplasms that caused ulcers were mast cell cause less dilation. Although obstruction tends to cause
tumor and gastrinoma [23].
focal rather than generalized dilation, generalized dilation
could be caused by a distal obstruction or volvulus around
22.3.8 Gastrointestinal Parasites the mesenteric root. Generalized, mild dilation is most
likely caused by enteritis or aerophagia. The appearance of
Roundworms are occasionally seen as an incidental find- different populations of intestine on radiographs or ultra-
ing on ultrasonography or may be the cause of obstruc- sound should be investigated. In one report of two cats
tion. In one cat, roundworms were seen as linear with intestinal volvulus, the abnormal population of intes-
structures with hyperechoic margins and a hypoechoic tine in one cat exhibited asymmetric thickening of wall lay-
center. There was no deep acoustic shadowing and fluid ers with preservation of wall layering. Free abdominal fluid
was seen in the lumen of the intestine. Similar reports in was present consistent with a loss of serosal detail seen
cats have described the transverse appearance as being radiographically. A second cat had stacked loops of dis-
target‐like with the outside being hyperechoic and the tended small intestine. Surgery was recommended without
center hypoechoic [24]. additional imaging because occasional gas bubbles in the
A parasite with characteristics similar to Spirocerca lupi abdomen suggested perforation [29].
was found in a nodule in the pylorus of a vomiting cat [11]. The classic roentgen sign of mechanical ileus on survey
A similar parasite referred to as “Spirocerca felineus” has radiography is dilation of small intestine proximal to an
been identified in the GI tract of stray cats in India [25]. obstruction. Remember that proximal loops may be
This parasite appears to have been moved from the genus located caudal to an obstruction rather than cranially.
Spirocerca to Cylicospirura and has been reported in nod- Distended loops may be gas or fluid filled. There may be
ules in the stomach of cats in India and Australia [26].
multiple parallel loops (“stacked loops”) and the intestine
may be compressed at the turns (“hairpin” turns). The
22.4 Small Intestinal Disorders cause of obstruction may or may not be visible but
includes foreign bodies (Figures 22.6 and 22.13), neopla-
sia (Figure 22.12), trichobezoars [30], intussusception,
22.4.1 Ileus
or intestinal volvulus. Trichobezoars may present as a
Ileus can be functional (adynamic) or mechanical palpable mass that can be apparent radiographically as
(dynamic). In functional ileus, motility is decreased a heterogeneous fluid and gas opacity. Ultrasonography
or completely stopped (Figure 22.11). In mechanical or can be useful to determine the cause of obstruction and
dynamic ileus (Figures 22.6 and 22.12), there is a physical evaluate mesenteric lymph nodes [30].