Small Animal Radiology and Ultrasound: A Diagnostic Atlas and Text

Chapter Three The Abd omen 435
A
B
Fig. 3-242 Transverse (A and C)
and longitudinal (B) sonograms of
the caudal abdomen of a 10-year-old
female mixed breed dog with a history
of leucocytosis, abdominal pain,
and hypothermia. There is an elongated
oval structure in the caudal
abdomen that has a thick echogenic
wall and echogenic material within
the lumen. The structure divides into
two tubes in the transverse view (C).
This is indicative of an enlarged
uterus that contains echogenic fluid
and is therefore most likely a pyometra.
Diagnosis: Pyometra.
C
Fig. 3-243 Longitudinal sonograms
of the uterus of a 13-year-old female
Cocker Spaniel with a history of a
mucoid vaginal discharge of 1
month duration. There is uterine
enlargement with multiple hypoechoic,
irregularly shaped lesions
within the wall of the uterus. This is
indicative of inflammatory or infiltrative
disease of the uterine wall.
Diagnosis: Cystic endometrial
hyperplasia.
The anestrus uterus may be identified as a tubular structure with hypoechoic walls and
a minimally hyperechoic lumen. It may be identified dorsal to the urinary bladder and can
be traced cranially with difficulty because of overlying small intestines. The laminar structure
of the uterine walls, although recognized, is much less notable than that associated
with the alimentary tract. It is the dominant echogenic strips in the intestine that facilitate
its differentiation from uterus sonographically.
Using high-frequency transducers, pregnancy can be detected as early as 10 days in experimental
dogs and 4 days in cats. 826-841 In most cases, a pregnancy can be confirmed by 17 to
20 days gestational age. The accuracy with which a diagnosis of pregnancy can be made is
nearly 99% by 28 days even with somewhat uncertain breeding dates. The blastocyst appears
as a focal, slightly hyperechoic area in the uterine horn. A small central hyperechoic area may
be observed within the blastocyst. As the blastocyst enlarges, the uterus becomes less tubular
and segmentation can be observed. The diameter of the gestational sac varies even among
fetuses in the same litter. In the dog, fetal cardiac activity can be identified at 20 days, and in