Small Animal Radiology and Ultrasound: A Diagnostic Atlas and Text

446 Small Animal Radiolo g y and Ultrasono graphy
Fig. 3-261 Longitudinal (A and B)
and transverse (C and D) sonograms
of the prostate of a 9-year-old male
mixed breed dog with a history of
stranguria for 4 months. There is an
anechoic septated structure located
cranial to the prostate and lateral to
the urinary bladder. The anechoic
lesion can be identified lateral, ventral,
and to the right of the prostate
in the transverse sonograms. This is
indicative of a paraprostatic cyst.
Diagnosis: Paraprostatic cyst.
A
B
C
D
TESTICLES
Unless they are enlarged, undescended testicles are rarely radiographically apparent. They
may be found anywhere from just caudal to the kidneys to the inguinal ring (Fig. 3-262).
Intraabdominal testicles are prone to neoplastic changes, especially Sertoli cell tumors. In
these cases, a large abdominal mass may be accompanied by prominent nipples. Another,
less common cause of enlargement of a retained testicle is torsion. 879 Although most scrotal
testicular tumors are benign, extension of a tumor along the epididymis may be recognized
radiographically as an irregular enlargement extending through the inguinal ring
into the sublumbar area.
Intrascrotal testicles may undergo a torsion resulting in swelling and pain in the malpositioned
testicle. 880,881 In addition to testicular torsion and testicular neoplasia other
entities such as orchitis, testicular trauma or hematoma, testicular vascular abnormalities,
scrotal hydrocele, and ciliary dyskinesis should also be considered. 882-884 Although
intrascrotal abnormalities are directly accessible via palpation, they are best assessed by
ultrasonography.
U LT R A S O N O G R A P H Y O F T H E A B N O R M A L T E S T I C L E
Usually, testicular tumors are hypoechoic, but they also may be heteroechoic or
hyperechoic relative to the surrounding normal testicle. Most are well circumscribed and
round or oval. The size of the tumor and the sharpness of the interface between the tumor
and the normal testicular tissue determine the echogenicity of the tumor. Smaller tumors
tend to be hypoechoic, while larger tumors are often heteroechoic. Only a few hyperechoic
tumors have been reported. Smaller tumors also tend to have sharper margins and larger
tumors are often poorly demarcated from the surrounding normal tissue. 885-887 Small
masses that cannot be palpated can be detected using ultrasonography. A consistent sonographic
pattern has not been associated with tumor type (Figs. 3-263 and 3-264).
Intraabdominal retained testicles can be identified accurately using ultrasonography