A review of pyometra in small animal medicine: incidence, pathophysiology, clinical diagnosis, and medical management

Abstract

Pyometra is a common reproductive disorder involving an acute or chronic bacterial infection of the uterus, with accumulation of purulent exudate in the lumen. This disorder is hormonally driven, primarily by uterine exposure to progesterone and estrogen priming during repeated estrous cycles. Traditionally, pyometra is thought to occur in conjunction with cystic endometrial hyperplasia as “cystic endometrial hyperplasia-pyometra complex”. Cystic endometrial hyperplasia commonly, but not necessarily, precedes development of pyometra. Pyometra is more widely recognized as a reproductive condition of bitches, but can also occur in queens. Pyometra is classified as being either open- or closedcervix, based on the presence or absence of vaginal discharge. Diagnosis of pyometra is based on reproductive history, clinical signs, blood work, and imaging. Depending on extent of endotoxemia and cervical patency, patient presentation is variable, ranging from mild clinical signs to decompensated shock. Regardless, pyometra should be considered a potentially life-threatening medical emergency, independent of apparent stability, since sepsis, peritonitis, and uterine rupture are possible sequelae. In all cases, initial stabilization and institution of appropriate antibiotic therapy are warranted. Ovariohysterectomy is the traditional treatment of choice for pyometra. Recently, medical management has become a viable alternative to ovariohysterectomy, enabling preservation of future fertility of bitches and queens. The most effective medical protocols involve low-dose prostaglandin treatment in conjunction with antiprogestins or dopamine agonists. Although medical therapy can be effective in stable cases, recurrence during future estrous cycles is common.