Small Animal Radiology and Ultrasound: A Diagnostic Atlas and Text

Chapter Three The Abd omen 381
SIMPLE RENAL CYST. A smoothly marginated lucency with a well-defined circumferential
rim of functional renal tissue will be seen during the nephrogram. Depending on the
location of the cyst, the collecting system may be distorted (Fig. 3-157).
Unilateral, Small, Regular
Feline and Canine. The urographic changes described in bilateral hypoplasia and
CIN are the same in unilateral disease for the affected kidney.
Unilateral, Small, Irregular
FeLINE AND CaNINE. The urographic changes described in bilateral cases of CIN, chronic
pyelonephritis, and renal infarcts are the same in unilateral disease for the affected kidney.
Normal Size and Shape
FELINE AND CANINE
ACUTE TUBULAR NEPHROSIS. Acute tubular nephrosis may be induced by excretory
urography. The urographic findings are a nephrogram phase that persists or becomes progressively
more dense with time. A pyelogram phase usually is not noted (Fig. 3-158). In
such instances, treatment with intravenous fluids and diuretics should be instituted.
ACUTE PYELONEPHRITIS, INTERSTITIAL NEPHRITIS, AND GLOMERULAR NEPHRITIS.
Depending upon the severity of the condition, the EU may be normal. If the condition is
severe, a faint nephrogram image or renal pelvic and ureteral dilation may be seen.
RENAL CALCULI. The nephrogram findings should appear normal and the pyelogram
will reveal a radiolucent filling defect within the collecting system. If the calculus has
caused obstruction, dilation of the renal sinus and possibly of the diverticula may be seen.
Because pyelonephritis frequently is seen in association with renal calculi, the changes associated
with pyelonephritis also may be identified.
NEPHROCALCINOSIS. A normal to faint nephrogram image may be present, depending
upon the extent of the renal parenchymal injury associated with the nephrocalcinosis. The
pyelogram image will be normal or slightly irregular; however, filling defects will not be
identified.
KIDNEY RUPTURE. The perirenal area will be hazy on survey radiographs. The EU will
usually, but not necessarily, show extravasation of contrast medium into the surrounding
soft tissues if the rupture extends into the pelvis. 470 The kidney may not excrete contrast.
If the rupture is close to the renal pelvis, dilation of the pelvis and pelvic recesses may be
present.
Fig. 3-157 A 12-year-old male mixed breed dog with mild paraparesis.
On physical examination an enlarged left kidney was palpated.
Survey radiographs revealed that the cranial pole of the left
kidney was enlarged. The excretory urogram revealed that the cranial
pole of the left kidney was enlarged, with a fine rim of contrastenhanced
renal tissue (white arrows) surrounding a relatively radiolucent
mass. The cranial urinary collecting structures appear to be
displaced caudally. Differential diagnoses include renal cyst, renal
neoplasia, renal granuloma, or renal abscess. Diagnosis: Simple renal
cyst.