Today's Veterinary Practice

NOV-DEC 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 NOVEMBER/DECEMBER 2018 the left of the screen, indicating that the transducer marker (or "notch") is pointing cranially, along the long axis of the patient. Then rotate the transducer 90° so that the notch points toward the patient's right side. This results in the right side of the dog or cat being oriented toward the left-hand side of the ultrasound image on the screen, as viewing a ventrodorsal radiograph of the abdomen. Diaphragmatic–Hepatic Window To obtain the diaphragmatic-hepatic (DH) window, place the transducer in a subxiphoid location. Sufficient image depth and cranial angulation of the beam are necessary to visualize the interface of the hyperechoic, curvilinear diaphragm-lung interface with the coarse echotexture of the hepatic parenchyma. Image depth and focus should be optimized such that the diaphragm is located in the far field of the image display. Fan the ultrasound beam to the patient's left and right, following the contour of the diaphragm, while maintaining a sagittal imaging plane along the long axis of the patient. In a normal patient, the liver and diaphragm remain in direct contact. If peritoneal effusion is present at this window, it may appear as anechoic material between the liver and diaphragm or between liver lobes ( FIGURE 2 ). Gallbladder Assessment A complete assessment at the DH window includes an assessment of the gallbladder and transdiaphragmatic visualization of the pericardium. The gallbladder is positioned to the right of midline between the right medial and quadrate lobes of the liver in the dog and within the right medial lobe in the cat. In normal dogs and cats, the gallbladder appears as a thin-walled, ovoid to rounded structure containing anechoic material. In a typical small to medium-size dog, the gallbladder can easily be found from the original subxiphoid position by fanning the probe toward the patient's right. Subtle abnormalities of the gallbladder may not be readily apparent during the AFAST examination; however, the combined presence of a large volume of organized, nonmobile gallbladder contents, anechoic surrounding fluid, and hyperechoic adjacent fat (representing steatitis) should raise concern for gallbladder leakage, rupture and peritonitis. 8 Pericardial Assessment The DH window provides a good acoustic window to the heart. In cats and small and medium-size dogs, minimal adjustment of imaging parameters (depth and focus) will be necessary to visualize the apical portion of the heart. If readily apparent, pericardial effusion can be seen as anechoic material surrounding the cardiac apex, bordered by a thin, echogenic interface representing the pericardium. Using this window alone, it may not be possible to differentiate between pericardial and pleural effusion; thus, a complete TFAST examination is warranted in dogs or cats when pleural or pericardial effusion is present. Splenorenal Window If the patient is positioned in left lateral recumbency, the splenorenal (SR) window will be located within FIGURE 2. Diaphragmatic-hepatic window showing the liver (L), diaphragm (D), and a large volume of interposed peritoneal effusion (E). FIGURE 3. Splenorenal window showing the left kidney (LK) and a large volume of peritoneal effusion (E). The large volume of effusion has displaced the spleen out of the current window.

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