Today's Veterinary Practice

MAR-APR 2018

Today's Veterinary Practice provides comprehensive information to keep every small animal practitioner up to date on companion animal medicine and surgery as well as practice building and management.

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PEER REVIEWED 60 IMAGING ESSENTIALS Colon All parts of the colon are fully evaluated by beginning at the level of the ileocecocolic junction in the cat and ileocolic junction in the dog and sweeping the transducer cranially along the ascending colon. The ascending colon is a short segment of large intestine in the right cranial abdominal quadrant. Continue leftwards along the transverse colon. The transverse colon spans the right to left cranial abdomen and can readily be identified using the stomach as a landmark; it is located immediately caudal to the greater curvature of the stomach ( FIGURE 1 ). Finish scanning the colon by continuing caudally along the descending colon. Using the urinary bladder as a landmark to identify the descending colon ( FIGURE 2 ), a reversed approach (descending colon, transverse colon, and then ascending colon) can also be used. The descending colon, usually containing gas or feces, is located immediately dorsal to the urinary bladder, within the far field of the image. TABLE 1 Normal Ultrasonographic Measurements (95% Confidence Intervals) of Gastrointestinal Tract Wall Thickness in Dogs and Cats SEGMENT OF GASTROINTESTINAL TRACT DOG WALL THICKNESS CAT WALL THICKNESS Stomach 3 − 5 mm 1 2 mm (inter-rugal) 2,3 and 4 mm (rugal fold thickness) 2 Duodenum Up to 5 mm 4 2 − 2.5 mm 5,6 Jejunum 2 − 5 mm 5 2 − 2.5 mm 5,6 Ileum 2 − 4 mm 5 2.5 − 3.2 mm 2,5,6 Colon 2 − 3 mm 5 1.4 − 2.5 mm 5 Cecum 1.5 mm 7 1.5 − 2 mm 8-10 Note: Normal ultrasonographic measurements of the individual layers of the canine 11 and feline 6,12 gastrointestinal tract have been described in recent literature. BOX 1 Criteria for assessing the ileum and colon include: Uniformity in diameter Wall thickness ( TABLE 1 ) Discrete wall layering Presence of luminal contents Peristalsis FIGURE 1. Short axis view of the transverse colon in a dog; the transverse colon is located caudal to the liver and stomach. On this sagittal image of the abdomen (cranial is to the left), note the thin walled, gas filled transverse colon with dirty acoustic shadowing. FIGURE 2. Short axis view of the caudal aspect of the descending colon in a dog. Note the thin walled ( white arrowhead ), gas filled descending colon with dirty acoustic shadowing. The urinary bladder is used as a landmark to find the descending colon in the far field of the image.

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