Page 2334 - Cote clinical veterinary advisor dogs and cats 4th

Radiographic Interpretation, Abdomen 1155.e5

Cat: diameter greater than 4 times the Dose: 1-3 mL/kg air per rectum. Use ○ Pneumoretroperitoneum may be a result of
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height of L2 vertebral endplate caution if the colon is friable to avoid pneumomediastinum or perineal trauma.
VetBooks.ir that is dilated (orad to the obstruction) Pancreas: Postprocedure
colonic rupture or venous uptake of gas.
Two populations of bowel are seen; one
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Additional imaging studies, or cytologic or
and one that is not (aborad to the
• Normal
obstruction).
a definitive diagnosis. Imaging modalities
Causes include foreign bodies (p. 353), ○ The pancreas is located along the caudal histologic information may be required for
margin of the stomach and duodenum,
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neoplasia, torsion, intussusception with the pancreatic body in the cranial should be thought of as complimentary to
(p. 561), intestinal entrapment, and duodenal flexure. other diagnostic tests.
stricture. ○ The normal pancreas is not seen radio-
○ Linear foreign body graphically in dogs but is occasionally seen Alternatives and Their
More common in cats than dogs in cats when surrounded by fat. Relative Merits
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Pleating or plication of small intestinal • Abnormal • Positive and negative contrast radiographic
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loops is seen. Loops may contain short ○ Characteristics of pancreatitis: possible studies of the GI and urinary tract may
tubular or comma-shaped collections mass effect widening the angle of the provide additional anatomic and functional
of gas. cranial duodenal flexure, gas-filled duo- information. Procedures and Techniques
○ Functional (paralytic) ileus denum, caudal colonic displacement, and • Abdominal ultrasound can further character-
Distinguish functional from mechanical loss of cranial abdominal serosal detail. ize lesions and be used to guide fine-needle
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ileus. The latter requires surgery. Abdominal lymph nodes: aspiration.
A single population of mild to moderately • Normal • CT, in combination with angiography and
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dilated, often gas-filled, small-intestinal ○ Silhouetting often precludes evaluation of urography, provides additional anatomic,
loops is seen (generalized dilation). lymph nodes, even when enlarged. functional, and vascular information.
Causes include enteritis (p. 382), • Abnormal
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peritonitis, vascular compromise, or ○ Sublumbar lymphadenomegaly may be SUGGESTED READING
neuromuscular disease. seen distinctly ventral to L6 and L7 and Thrall DE, editor: Textbook of veterinary diagnostic
Large intestine: may be caused by genitourinary or pelvic radiology, ed 7, St. Louis, 2018, Saunders.
• Normal limb diseases.
○ Canine cecum: a curled, usually gas-filled Peritoneal and retroperitoneal space: ADDITIONAL SUGGESTED
structure in the right mid-abdomen • Normal READINGS
○ Feline cecum: rarely seen radiographically ○ Fat provides a natural contrast (serosal O’Brien R, et al, editors: BSAVA manual of canine
○ Colon: a tubular structure that starts at the detail) around the soft-tissue–opacity organs and feline abdominal imaging. Quedgeley, UK,
cecum, crosses the abdomen transversely, of the abdomen and retroperitoneum. 2009, British Small Animal Veterinary Association.
and extends caudally toward the pelvic • Abnormal Thrall DE, et al, editors: Atlas of normal radiographic
inlet ○ In emaciated and immature animals, anatomy and anatomic variants in the dog and cat,
○ Dog: colonic diameter less than the length retroperitoneal and abdominal serosal ed 2, St. Louis, 2015, Saunders.
of L7 vertebral body detail is poor.
○ Feline: colonic diameter less than 2.8 times ○ Mass effect, effusion, carcinomatosis, RELATED CLIENT EDUCATION
the length of L2 cranial endplate peritonitis (p. 779), and pancreatitis (pp. SHEET
• Abnormal 740 and 742) may cause decreased serosal
○ Colonic dilation may be due to constipa- or retroperitoneal detail. Consent to Perform Radiography
tion (p. 202), obstruction, or a neurologic ○ Free intraabdominal gas is seen as pockets
disorder. of gas that tend to accumulate caudal AUTHOR: Aisha N. Young, DVM, MVSc, DACVR
○ Colonic torsion often leads to severe to the diaphragm. Suspect ruptured EDITORS: Leah A. Cohn, DVM, PhD, DACVIM; Mark S.
colonic distention and malpositioning abdominal viscus or external puncture Thompson, DVM, DABVP
of the colon. unless recent surgery. Intraabdominal
○ A pneumocolon can be rapidly performed gas may be detected for several days to
to distinguish large from small intestine. several weeks after laparotomy.

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