Feline Pyometra Study Guide

Overview and Clinical Importance

Pyometra (literally meaning "pus-filled uterus") is a potentially life-threatening bacterial infection of the uterus characterized by accumulation of purulent exudate in the uterine lumen. While less common in queens than in bitches, feline pyometra represents a true veterinary emergency requiring prompt diagnosis and treatment.

In queens, approximately 2.2% are diagnosed with pyometra before 13 years of age, with an incidence rate of 17 cats per 10,000 cat-years at risk. The mean age at diagnosis is 5.6 years (range: 10 months to 20 years), with incidence increasing markedly after 7 years of age.

Etiology and Pathophysiology

The Role of Progesterone

Pyometra develops during the luteal phase (diestrus) when progesterone dominance creates conditions favorable for bacterial infection. Unlike dogs with spontaneous ovulation, cats are induced ovulators; however, spontaneous ovulation can occur in group-housed queens or those with repeated follicular activity.