Pyometra in Dogs

Often, veterinarians encourage pet owners to sterilize their pets if there is no intention of breeding them, especially female dogs. This is because unsterilized female dogs have higher chances of having health complications, and Pyometra is one of them. 


Pyometra is a bacterial infection in the uterus and it is a life-threatening condition especially for unsterilized female dogs. When dogs are on heat, the hormone progesterone remains elevated up to 1-2 months, causing uterus lining to thicken to prepare for pregnancy. However, if the pregnancy does not occur for several heat cycle, the uterine lining (inner layer of the uterus) will continue to thicken until cysts (a condition called cystic endometrial hyperplasia) form in it.


Anatomy of dog’s uterus

The thickened cystic lining produces fluids that create an ideal environment for bacterial growth. During every heat cycle, the cervix will be open, and bacteria can easily enter the uterus. This leads to infection and development of pus. Which is what we call pyometra.

The difference between healthy and infected uterus


Pyometra are most commonly found in dogs at the age between 6 - 12 years old and the typical time for pyometra to occur is about 2 - 8 weeks after heat cycle. Regardless of the dog’s age, pet owners must be attentive of any signs and symptoms during this crucial time.

The most common symptoms of pyometra are:

  • Decrease in appetite
  • Vomiting 
  • Diarrhoea 
  • Fatigue 
  • Bloated abdomen

As mentioned before, pyometra is a life-threatening condition which should be addressed as soon as possible. Emergency surgery is required. 

If pyometra is left untreated, the dog will have a high risk of sepsis (bacteria from infection gets absorbed into the bloodstream and it will be circulated around the body) and it can die from it. Multiple organ failure can result as well. The uterus when severely swollen with pus can rupture as well.

Dog with bloated abdomen due to pyometra


Bloodwork, radiographs (such as X-ray) and ultrasound are used to make a diagnosis of pyometra. Antibiotics alone is generally unable to effectively penetrate into the severely infected uterus. Pyometra is treated by surgically removing the infected uterus from the dog. 

X-ray of a dog with swollen and infected uterus

If you do not want your precious furry friend to go through this painful and risky phase, we strongly encourage you to spay your dog while they are young. We encourage sterilisation at 6 months old. Sterilisation is better done before their first heat, as this also lowers their risk of mammary cancer. Moreover, your wallet will thank you too as pyometra surgery costs much more than spay due to the complexity of the procedure.


Post by Nurse Kelly