Small Animal Radiology and Ultrasound: A Diagnostic Atlas and Text

Chapter Three The Abd omen 347
within the lumen of the cyst. The cysts did not communicate with the intestines and peristalsis
was not observed within the cysts.
L A R G E I N T E S T I N E
Size Changes. The normal colon may be empty or may contain air, fluid, or fecal material.
It varies in size and position depending on the amount and type of material present.
Normally the colon is no more than 3 times larger in diameter than the small bowel. When
the colon is severely distended, differential diagnoses should include atresia ani, colonic
obstruction, megacolon, volvulus, or obstipation (Fig. 3-123). 400-402
The colon can become distended if the animal is well trained and not allowed to go
outside to defecate. Therefore the size of the colon must always be evaluated relative to
Fig. 3-118 A 14-year-old neutered
male domestic short-haired cat had
been vomiting and had an abdominal
mass. An oblique sonogram
revealed a normal intestinal loop
(short arrows) and a focal, severe,
concentric thickening of the
mucosa-submucosa-muscularis
layer (largest arrows), which arises
abruptly from the normal-sized loop
of intestine (medium-sized arrows).
Diagnosis: Intestinal adenocarcinoma.
Fig. 3-119 A 9-year-old Yorkshire
Terrier had been vomiting and had
an abdominal mass. A longitudinal
sonogram reveals a large, eccentric,
hypoechoic mass arising from the
mucosa-submucosa-muscularis
layer (black arrows). The mucosal
lumen is identified as the white linear
structure (white arrow).
Diagnosis: Leiomyosarcoma.