What Is Pyometra?
Pyometra is a life-threatening bacterial infection of the uterus that occurs in intact (unspayed) female dogs and cats. The uterus fills with pus, and without emergency surgical treatment, the condition is fatal. It typically occurs in middle-aged to older females 4–8 weeks after a heat cycle. Spaying completely and permanently prevents pyometra.
Understanding Pyometra
Pyometra develops because progesterone levels after oestrus thicken the uterine lining and suppress local immune responses, creating an ideal environment for bacterial colonisation — usually by E. coli bacteria from the gastrointestinal tract. The condition exists in two forms: open cervix pyometra, where pus drains vaginally (visible as a foul-smelling discharge), and closed cervix pyometra, where the cervix is closed and pus builds internally — the more dangerous form because it shows fewer external signs.
Symptoms vary by type. Open pyometra: foul-smelling vaginal discharge, increased water intake and urination, lethargy. Closed pyometra: more subtle and rapidly life-threatening — distended abdomen, vomiting, severe lethargy, and collapse without obvious discharge. Any intact female dog or cat showing lethargy, increased drinking, or abdominal distension 4–8 weeks after a heat cycle should be seen urgently.
Emergency surgical spaying (ovariohysterectomy) is the treatment of choice and is curative. Medical management with prostaglandins exists but is reserved for breeding animals, carries a lower success rate, and carries significant risk — it is not appropriate for severe or closed cases. Recovery after successful surgery in otherwise healthy animals is typically excellent.