This document summarizes information about pyometra, an infection of the uterus that results in pus accumulation. It defines pyometra and classifies it as either open or closed. Open pyometra involves a discharge from the vagina while closed pyometra does not. Common causes are hormonal and structural changes to the uterus from aging and heat cycles. Symptoms can include vomiting, loss of appetite, and fever. Diagnosis involves blood tests, x-rays, and ultrasounds. Treatment is usually a surgical removal of the uterus and ovaries, while in some cases prostaglandins may be used to medically treat the condition in valuable breeding animals. Prevention involves early spaying of pets.