Pyometra is a life-threatening uterine infection that affects unspayed female pets. The older a pet becomes and the more heat cycles she has, the more likely she is to develop pyometra. The West Vets Emergency Veterinary Clinic team wants to ensure you understand the risks of leaving your female pet intact and what to do if your furry pal develops pyometra signs. This guide details everything you should know about pyometra in female dogs and cats. 

What is pyometra in pets?

Pyometra is a bacterial uterine (i.e., womb) infection that occurs in unspayed female pets. When a pet develops pyometra, bacteria and pus build up inside the uterus, stretching and damaging the uterine walls and causing toxins and bacteria to leak out. Once infection reaches the abdominal cavity and bloodstream, affected pets can go into shock or die.

The rate at which pyometra becomes life-threatening depends on the type. An open pyometra means the cervix—the opening between the uterus and vaginal canal—is open, allowing some of the pus and debris to drain. An open pyometra is considered less severe than a closed pyometra, where the pus and bacteria become trapped inside the uterus.

What causes pyometra in pets?

Hormonal changes during a pet’s normal heat cycle can lead to pyometra. Progesterone causes the uterine lining to thicken in preparation for pregnancy, but if pregnancy does not occur, the lining does not shed. Over time, repeated cycles cause the lining to continuously thicken, which creates a welcoming environment for bacteria. A common bacterial culprit is E. coli, which can ascend from the pet’s gastrointestinal (GI) tract. 

What are pyometra signs in pets?

Being able to recognize pyometra signs is critical for early intervention, which can be life-saving. Signs vary depending on whether the pyometra is open or closed but commonly include the following:

  • Vaginal discharge
  • Lethargy
  • Appetite loss
  • Increased thirst and urination
  • Vomiting or diarrhea
  • Fever

How do veterinarians diagnose pyometra in pets?

Pyometra is always high on the list of suspected causes when an intact female pet gets sick; however, confirming this diagnosis sometimes requires multiple tests, especially if the pyometra is closed and no vaginal discharge is present. Diagnosis starts with a thorough physical exam and may also require the following tests:

  • Blood work 
  • Urinalysis
  • X-rays
  • Ultrasound

How do veterinarians treat pyometra?

The primary pyometra treatment is surgical removal of the infected uterus and ovaries. Although similar to a traditional spay, pyometra surgery is considerably more difficult because the uterus is fragile, and the surgeon must take care to avoid rupturing these tissues and releasing infection into the abdomen. Pets must be stabilized and placed on intravenous (IV) fluids and antibiotics before surgery to reduce anesthetic risks and ensure the best outcome. In rare cases, such as when a pet is a poor surgical candidate or a highly valuable breeding animal, medical management may be attempted but is often unsuccessful. Pets may stay in the hospital overnight or for several days after surgery to receive ongoing intensive care. Once released, most pets go home on oral antibiotics and pain medications.

How can pet owners prevent pyometra?

The most effective way to prevent pyometra is to have your female pet spayed. Spaying also prevents unwanted pregnancies and dramatically reduces the risk of mammary (i.e., breast) cancer, which is often deadly. The best time to spay your pet is before the first or second heat cycle, however, older pets can also benefit from spay surgery. Breeders should plan to spay females as soon as they are retired.

Having your female pet spayed is the best way to prevent them from developing pyometra and other reproductive health problems. When a pet remains intact for any reason, pet owners should learn to recognize pyometra signs and take action immediately if signs develop. Pyometra is a true emergency, so contact our West Vets Emergency Veterinary Clinic team if you suspect your intact female pet has developed this life-threatening infection.