Ultrasonographic and computed tomographic characterization and localization of suspected mechanical gastrointestinal obstruction in dogs.

OBJECTIVE To evaluate the usefulness of noncontrast abdominal CT and abdominal ultrasonography for the detection of mechanical gastrointestinal obstruction in dogs and compare intestinal diameter ratios between dogs with and without obstruction. DESIGN Controlled trial. ANIMALS 16 client-owned dogs with physical and radiographic findings consistent with mechanical gastrointestinal obstruction. PROCEDURES Abdominal ultrasonography and CT were performed for all dogs, followed by laparoscopy and exploratory laparotomy. Time required for image acquisition and presence and location of gastrointestinal obstruction were assessed with both imaging modalities. Findings were compared with those of exploratory surgery. Maximum and minimum intestinal diameters were recorded on CT scans; values were converted to a ratio and compared between dogs with and without obstruction. RESULTS Results of abdominal CT and exploratory surgery for the diagnosis of mechanical obstruction agreed for all 16 dogs; 10 dogs had complete obstruction, 3 had partial obstruction, and 3 had no obstruction. In 1 dog with functional ileus, abdominal ultrasonography resulted in an incorrect diagnosis of mechanical obstruction. Median (interquartile range) image acquisition time for abdominal CT (2.5 minutes [2.0 to 3.8 minutes]) was markedly and significantly shorter than that for ultrasonography (26.0 minutes [22.0 to 35.8 minutes]). In both dorsal and transverse CT planes, dogs with gastrointestinal obstruction (partial or complete) had significantly larger intestinal diameter ratios than dogs without obstruction. CONCLUSIONS AND CLINICAL RELEVANCE Abdominal CT was feasible, rapid, and accurate for the diagnosis of mechanical obstruction in dogs with clinical signs and physical examination findings consistent with partial or complete gastrointestinal obstruction.