Abdominal ultrasonography is the preferred method for evaluating patients for pyometra. The most common ultrasonographic finding
is distention of the uterus with an anechoic to hyperechoic fluid (Figure 2).31,32 A thickened and cystic endometrium is suggestive of concurrent cystic endometrial hyperplasia.33 In patients with uterine rupture, free fluid may be identified within the abdominal cavity, and the omentum may be hyperechoic
secondary to bacterial peritonitis. Abdominal ultrasonography can also be used to exclude other conditions that can cause
uterine enlargement or vaginal discharge, such as early pregnancy.
Figure 2. An ultrasonographic image of an enlarged and tortuous uterine horn filled with an anechoic to hypoechoic fluid.
Vaginal cytology in patients with open-cervix pyometra will typically demonstrate excessive numbers of degenerate neutrophils
and intracellular and extracellular bacteria (Figure 3).12 A cytologic finding of inflammation can be seen in patients with vaginitis and, thus, is not diagnostic of pyometra without
additional confirmatory testing. The absence of excessive neutrophils and bacteria in the vaginal discharge would warrant
reconsideration of the cause of the patient's condition. Meanwhile, vaginal cytology findings in patients with completely
closed-cervix pyometra may only reflect the patient's stage of estrous cycle. Expected cytologic findings during diestrus
would include a predominance of intermediate and parabasal cells and, early in diestrus, an influx of nondegenerate neutrophils.
Figure 3. Degenerative neutrophils with intracellular bacteria present in vaginal discharge from a dog with open-cervix pyometra.
For guidance on how to treat canine pyometra—whether medically or surgically—see the article Surgical and medical treatment of pyoderma.
Brain Lucas Hamm, DVM
Jeff Dennis, DVM, DACVIM
BluePoint Specialty & Emergency Medicine for Pets
11950 W. 110th St., Suite B
Overland Park, KS 66210