Pyometra in dogs is a bacterial infection of the uterus, usually seen in unspayed females. After a heat cycle, hormones (especially progesterone) cause the uterine lining to thicken, creating a favorable environment for infection.

When bacteria (often E. coli) enter the uterus, pus builds up, leading to severe illness.

Types of pyometra in dogs:

• Open Pyometra – pus drains through the vulva (easier to detect).
• Closed Pyometra – pus is trapped inside; symptoms may remain hidden until the dog is critically ill.