Small Animal Radiology and Ultrasound: A Diagnostic Atlas and Text

272 Small Animal Radiolo g y and Ultrasono graphy
Fig. 3-24 Transverse sonograms of the urinary bladder of a 6-yearold
spayed female mixed breed dog with a history of chronic urinary
tract infection. An echogenic swirl of urine has created the turbulence
visible in the dorsal left side of the urinary bladder (arrows). This is the
result of urine being propelled into the bladder lumen from the
ureteral papillae. This occurs when the specific gravity of the urine
within the bladder is different from that in the ureter. This is a normal
phenomenon and has been termed a ureteral jet. Diagnosis: Ureteral
jet.
Uterus. The body of the uterus is located between the urinary bladder and the colon. It is
not seen routinely in the normal nongravid female. In fat patients, the uterine body may be
seen as a tubular soft-tissue structure located between the colon and the bladder or superimposed
on the urinary bladder. 50
Hysterography has been used for evaluation of uterine abnormalities. Catheterization
of the cervical canal is followed by slow injection of iodinated contrast medium.
Intrauterine pressure is monitored during the contrast injection, and the injection is terminated
when the pressure reaches 100 mm Hg. This technique has been used on a limited
basis, mostly because of the difficulty in catheterization and the variability of achieving
flow through the cervix into the uterus. 51,52 Ultrasonography is much more useful than
hysterography for evaluation of uterine abnormalities.
The uterine body may be identified during an ultrasonographic examination. It can be
identified either dorsal or dorsolateral to the urinary bladder (Fig. 3-26). It is usually easier
to detect it when examining the bladder in a transverse plane. It appears as a round heteroechoic
structure with a very small, mildly hyperechoic lumen. 39 It may also be examined
in a longitudinal axis, but orienting the transducer to the uterine body is more difficult.
The uterus must be distinguished from adjacent loops of intestine. However, the normal
uterus usually lacks the echogenic luminal stripe associated with intestines. In some cases
a minimal central stripe may be seen in the normal uterus, particularly during estrus.
Prostate. In male dogs, the prostate is immediately caudal to the urinary bladder and completely
surrounds the urethra. Normally, the prostate does not extend cranial to the pelvic
brim in young, sexually mature dogs. In chondrodystrophic breeds, it is common to see
some of the prostate’s perimeter cranial to the brim of the pelvis. When the bladder is distended
it may pull the prostate cranially.
Criteria for determining normal prostatic size have been published but are not used
routinely because of the somewhat cumbersome methodology. 53,54 The most useful