Pyometra: A Preventable Pet Disease

What is pyometra?

Pyometra describes a bacterial infection of the uterus (womb) and usually manifests with a pus-filled uterus. It means intact (unspayed) female pets are at the highest risk for this condition.

Pyometra makes your intact female pet very ill and can be life-threatening. It occurs because some of the toxins may leak into the affected pet’s bloodstream, causing widespread infection (sepsis). Pyometra must be treated quickly and vigorously to save a pet’s life.

When does pyometra commonly occur?

Pyometra usually occurs 4 to 6 weeks after a heat cycle in unspayed female dogs and cats.

How does pyometra happen?

During the heat cycle, the female body undergoes hormonal changes that alter the lining of the uterus to prepare for pregnancy. Unfortunately, the uterine changes also support invading bacteria to grow and reproduce which = infection. So if bacteria enter the uterus during estrus, this is bad news!

Where do pyometra-causing bacteria come from?

The bacteria are typically found in the areas of a pet’s intestines and vagina (For example E. coli).
Many of the infections are considered either from an ascending infection from the vagina, a concurrent urinary tract infection, or fecal contamination.

Which animals are susceptible to pyometra?

Any intact females are at risk. Typically, pyometra occurs in older dogs and cats because they have experienced many heat cycles. With each heat cycle, the hormonal effects on the uterus accumulate.

What are the common symptoms?

Lethargy (decreased energy levels)

  • Anorexia (refusing food)
  • Excessive water intake and/or excessive urination
  • Vomiting
  • Vaginal discharge containing blood and/or pus* (this may not occur in “closed” pyometra)

If you see any of these symptoms or are simply concerned, please contact us!

How is pyometra diagnosed?

Pyometra should be suspected in any unspayed female animal.
Confirmation of the condition involves:

  • Gathering the pet’s history (e.g. seeing if the pet has been drinking a lot of water and/or urinating
    more frequently)
  • Veterinarian conducting a physical examination, imaging (x-rays or ultrasound)

What are the treatment options for pyometra?

The optimal treatment involves spaying the affected dog or cat. Spaying (ovariohysterectomy) is surgical removal of the uterus and ovaries once the pet has been stabilized.

Because pyometra is a bacterial infection, the pet will be prescribed oral antibiotics and these should be continued for 7–10 days after surgery.

Occasionally breeding animals may be treated using medical therapy, but these treatments do not guarantee full recovery and pyometra recurrence is likely.

Spaying your dog or cat prevents pyometra and other conditions.
We welcome any questions regarding spaying or other preventive care!


  • Brooks, Wendy. “Pyometra in Dogs and Cats – Veterinary Partner.” Veterinary Partner, Veterinary Information Network, 2016 Retrieved from:
  • Memon, Mushtaq A. “Pyometra in Small Animals.” Merck Veterinary Manual. Retrieved from:
  • N.B. “Pyometra.” Small Animal Topics: Pyometra, American College of Veterinary Surgeons. Retrieved from: