Small Animal Radiology and Ultrasound: A Diagnostic Atlas and Text

444 Small Animal Radiolo g y and Ultrasono graphy
Fig. 3-258 Transverse (A to C) and
longitudinal (D) sonograms of the
prostate of a 9-year-old male mixed
breed dog with a history of stranguria
and incontinence of 3 months
duration. The prostate is hyperechoic
with multiple hypoechoic-toanechoic
irregularly shaped lesions
within the prostatic tissue. These are
indicative of prostatic cysts or
abscesses. Diagnosis: Prostatic
abscesses.
A
B
C
D
solely on the ultrasonographic examination. Prostatitis may produce multifocal anechoic
and/or hypoechoic areas with smooth or irregular margins. These lesions result from focal
inflammation or abscess formation. Hyperechoic areas that form shadows may indicate
prostatic mineralization, which may occur in either prostatitis or carcinoma but is more
common with carcinoma. Asymmetric enlargement may be seen more often with prostatic
tumor. Prostatic carcinoma may be characterized by multifocal hyperechoic areas that
have a tendency to coalesce. Round or oval hypoechoic masses, which represent sublumbar
lymph node enlargement, may be identified. Ultrasonography is more sensitive than radiography
in detecting sublumbar (iliac) lymph node enlargement. Identification of enlarged
lymph nodes during an ultrasonographic examination is a less specific finding and may
occur in association with either tumor or infection. If enlarged lymph nodes are recognized
on radiographs, neoplasia is most likely but a biopsy is required for a diagnosis.
Prostatic abscesses and intraprostatic cysts produce solitary or multiple hypoechoic
or anechoic lesions (Figs. 3-258 to 3-260). Posterior enhancement and through transmission
may be identified in cysts. Cellular echoes within the cavity may be present in
either cysts or abscesses. Cysts may be more smoothly marginated; however, either lesion
may have irregular margins. Tumor necrosis occasionally produces hypoechoic areas
within prostatic neoplasms, and this decreases the specificity of the ultrasonographic
findings.
Paraprostatic cysts are anechoic or hypoechoic structures that may be tubular or septated
(Fig. 3-261). Mineralization within the wall of the cyst may produce hyperechoic areas that
cause shadows. Infection or hemorrhage within the cyst may produce small echoes that move
with manipulation of the transducer or the patient. Communication of the paraprostatic cyst
with the prostate may be identified. Criteria that could separate infected from noninfected
paraprostatic cysts were not identified. 873 Distinguishing a large paraprostatic cyst from the
urinary bladder may be difficult, but with careful examination from all sides the distinction
can be made. If necessary, the bladder can be catheterized and saline can be injected through
the urinary catheter. The air bubbles within the fluid will be identified easily.