Small Animal Radiology and Ultrasound: A Diagnostic Atlas and Text

Chapter Three The Abd omen 429
Fig. 3-233 A 7-year-old female
domestic short-haired cat with
anorexia for 2 days. The lateral radiograph
revealed massive uterine
enlargement that displaced the
abdominal organs cranially and
slightly dorsally. Differential diagnoses
include uterine enlargement
(pregnancy, pyometra, or mucometra),
distention of the urinary bladder,
or mass arising from the caudal
abdominal organs. Diagnosis:
Pyometra.
monly are accompanied by a large amount of peritoneal fluid, usually due to tumor seeding
of the peritoneum, and this masks their presence. It must be remembered that the ovaries are
intraperitoneal. Therefore, depending on the size of the ovarian mass, it may be indistinguishable
from bowel and it will migrate to a position adjacent to the bowel. Mineralization
may be seen in ovarian masses, but it is not a reliable indicator of whether the mass is malignant
or benign. Ultrasonography can provide architectural insight on ovarian masses.
U T E RU S A N D VAG I N A
The uterus is not readily visualized by radiography unless it becomes enlarged. 50,757 In a fat
dog, the uterine body may be visible dorsal to or superimposed upon the bladder and ventral
to the colon on the lateral radiograph. When enlarged, the uterus becomes visible as a tubular
soft-tissue structure that displaces the small intestine cranially, dorsally, and toward the
midline. The uterus folds upon itself and appears oval or sausage shaped. Although fluidfilled
distended loops of intestine may create a similar appearance, the presence of gas within
the intestines is an important feature that helps to distinguish between an enlarged uterus
and distended small intestines. Uterine disease may be classified according to primary
changes in uterine location, such as torsion and herniation, and primary changes in the uterine
wall or lumen. 758-797 Diffuse enlargement of the uterus may be due to pregnancy, postpartum,
hemorrhage, infection such as pyometra or endometritis, accumulation of secretions
such as mucometra or hydrometra, subinvolution, or neoplasia (Fig. 3-233). 769-797 In both
the dog and the cat the differentiation of these conditions may be difficult based solely on
radiographic signs. If the cervix is open, allowing the uterus to drain, or if it is early in the
process, the uterus may not be readily apparent. In these instances, abdominal compression
may aid in defining the uterus (Fig. 3-234). Displacing the intestines cranially away from the
urinary bladder often allows the uterine body to become visible because it cannot be displaced.
Although pyometra usually involves the entire uterus, only one horn or only one portion
of one horn may be affected. Local or segmental uterine enlargement may be due to
segmental pyometra, neoplasia, granuloma, and retained fetal or placental remnants. In cats,
uterine infection may cause a series of segmental enlargements that mimic pregnancy (Fig.
3-235). Infection of the uterine stump in spayed dogs and cats may be recognized as a mass
between the colon and urinary bladder (Fig. 3-236). Tumors of the uterus may appear to be
focal masses, a segmental horn, or diffuse enlargement depending on whether or not the mass
limits passage of uterine contents (Fig. 3-237).
Contrast procedures for the canine or feline uterus are performed infrequently. These
can be technically difficult and require infusion of contrast medium through the cervix or
retrograde from the vagina. 798,799