Small Animal Radiology and Ultrasound: A Diagnostic Atlas and Text

378 Small Animal Radiolo g y and Ultrasono graphy
Bilateral, Small, Irregular
FELINE AND CANINE
CIN AND RENAL DYSPLASIA. The appearance is similar to that discussed above, except the
kidneys are irregularly shaped.
INFARCTS. These usually show a normal urogram with one or more focal flattenings
or indentations to the renal outline with regional areas of less opaque parenchyma (Fig.
3-152). Renal pelvic structures will appear normal.
CHRONIC PYELONEPHRITIS. The nephrogram phase may be normal or somewhat less
dense than normal. Stretching and slight dilation of the renal sinus with loss or irregularity
of the diverticula may be seen (Fig. 3-153). Focal flattenings or indentations of the renal
cortex peripheral to the areas of pelvic and pelvic recess irregularities may be present.
Unilateral, Large, Regular
Feline and Canine. The urographic changes described in bilateral obstruction causing
hydronephrosis, hyperplasia, lymphosarcoma, FIP, and primary and metastatic renal
tumors are the same in unilateral disease for the affected kidney.
PYONEPHROSIS. A rim of increased opacity with a relatively radiolucent center will be
seen during the nephrogram. There will be no pyelogram image (Fig. 3-154).
RENAL VEIN THROMBOSIS. Normal to reduced, but homogenous, opacification will be
seen during the nephrogram and may be delayed in onset. Usually, a pyelogram image will
not be seen. 193
Unilateral, Large, Irregular
Feline and Canine. The urographic changes described for bilateral cases of FIP and
lymphosarcoma are the same in unilateral disease for the affected kidney.
PRIMARY AND METASTATIC NEOPLASIA. Irregular areas of increased density may be seen
during the nephrogram phase. This is caused by variations in the vascularity of the neoplastic
tissue and the presence of islands of functional renal tissue (Fig. 3-155). The pyelogram
may reveal distortion of the collecting system if the mass is focal, or complete
obliteration or nonvisualization of the collecting structures if the lesion involves most of
the renal parenchyma (Fig. 3-156).
Fig. 3-152 A 12-year-old male
domestic short-haired cat with vomiting.
The survey radiographs
revealed slightly small, markedly
irregular kidneys. The excretory urogram
revealed slightly small renal
outlines with focal flattening of the
cortical borders (white arrows). The
renal sinus and proximal ureter of
the left kidney are slightly dilated.
Differential diagnoses include multiple
renal infarcts or chronic
pyelonephritis or both. Diagnosis:
Multiple renal infarcts with
pyelonephritis of the left kidney.