Pyometra

Pyometra is a potentially life-threatening uterine infection that affects intact female dogs and, less commonly, cats. It typically develops in middle-aged to older animals after repeated estrous cycles. The condition arises when progesterone during the luteal phase promotes cystic endometrial hyperplasia, creating an environment favorable to bacterial growth. Bacteria ascend from the vagina, with Escherichia coli among the most common pathogens.

Clinical forms are open pyometra and closed pyometra. In open pyometra, the cervix remains permeable and a vaginal discharge may be observed. In closed pyometra, the cervix is closed, and the uterus becomes distended with pus; this form carries a higher risk of rupture and peritonitis.

Diagnosis relies on history and physical examination, supported by laboratory and imaging tests. Complete blood count often shows leukocytosis with a left shift or leukopenia in septic patients. Serum chemistry may reveal electrolyte abnormalities and kidney involvement. Abdominal ultrasonography is particularly helpful, typically showing a dilated, fluid-filled uterus. Radiographs may reveal gas within the uterus or an enlarged abdomen.

Treatment is an emergency concern. The most effective and definitive therapy is surgical removal of the uterus and ovaries (ovariohysterectomy). Supportive care includes intravenous fluids and broad-spectrum antibiotics. Medical management using prostaglandins and antibiotics has been used in select open-pyometra cases when surgery is not possible, but it is slower and carries higher risks and a greater chance of recurrence or failure.

Prognosis depends on the form and the animal’s condition at presentation; open pyometra generally has a better prognosis than closed. With prompt treatment, many animals recover fully. Prevention is achieved through routine spaying of nonpregnant females.