Pyometra in Cats

Melissa Boldan, DVM
By Melissa Boldan, DVM on Feb. 3, 2022
cute cat meowing

In This Article


What is Pyometra in Cats?

Pyometra is an infection in the uterus. The term stems from the Latin words “pyo” (which means pus) and “metra” (which means uterus or womb). Translated, it means pus in the uterus. This condition occurs more frequently in older, unspayed female cats that have had several heat cycles in their lives without getting pregnant. Pyometra most commonly occurs in cats that have been in heat within the past month.  

When a cat is ready to mate and have kittens, she goes into “heat.” Heat is a term describing hormone changes inside the female animal’s body that makes them more receptive to getting pregnant. During this phase, your cat may be excessively vocal (yowling often) or stick her rear end up in the air. Following a heat cycle, hormones change, making it easier for bacteria to enter the uterus, grow and cause an infection.  

While pyometra is an uncommon condition in cats it can be life-threatening and requires emergency medical treatment.  

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Symptoms of Pyometra in Cats

The symptoms of pyometra can vary from subtle (almost unnoticeable) to severe lethargy, vomiting and weakness. Symptoms vary greatly because of a female cat’s opening from the vagina to the uterus called the cervix. This part of the body opens, or dilates, during labor and delivery, as well as during heat. It then closes following heat (or after a cat gives birth). If the cervix is still open, when pyometra develops, the pus can drain out of the body. Cats with an open cervix, or “open pyometra,” are much less sick than those with a closed cervix, “closed pyometra.”  

When the cervix is closed, it traps the pus inside the uterus which can result in the pet becoming septic and toxic shock developing quickly.  

Common signs of pyometra include:  

  • Pus draining from the vulva: This can be difficult to spot because cats are very meticulous about grooming. Watch for any drainage around the base of the tail or on bedding.  

  • Lethargy, depression, or weakness 

  • Anorexia or decreased appetite 

  • Increased thirst 

  • Vomit or diarrhea 

  • Fever 

Causes of Pyometra in Cats

Pyometra occurs in older intact female cats who have never given birth. This is because when a cat undergoes a heat cycle, several hormonal changes occur inside her uterus including thickening of the uterus walls. These changes are meant to prepare her body for pregnancy. Chronic thickening of the uterus walls without pregnancy may lead to a cyst forming in the walls of the uterus. Uterine cysts release fluid that feeds bacteria.  

The cat’s cervix also opens to allow sperm to enter. Meanwhile, her white blood cells that usually protect her from infection, are prevented from the uterus to protect the sperm. Unfortunately, this also protects bacteria, allowing it to rapidly multiply and grow in the uterus. As bacteria grows, pus accumulates and causes pyometra in cats.  

Rarely, a spayed cat may develop a pyometra, which is called a “stump pyometra.” When a female cat is spayed, her entire reproductive tract is removed, including the ovaries and the uterus. A stump pyometra occurs when an infection happens in the small amount of tissue (‘stump’) left behind after a spay is completed. This is very uncommon in cats.  

How Veterinarians Diagnose Pyometra in Cats

Your veterinarian will perform a thorough exam and review your cat’s health history. The veterinarian may ask the date of your cat’s last heat cycle and about any unusual behaviors at home including excessive drinking, wet spots, or discharge on your cat’s bedding.  

Your veterinarian will also perform tests, which may include: 

  • X-rays  

  • Blood work  

  • Urinalysis 

Diagnosing a pyometra in cats can be challenging when it is an open pyometra. Your vet may perform an ultrasound because this technique is more sensitive than x-ray and can detect changes in uterine size.  

Treatment of Pyometra in Cats

Pyometra in cats is most commonly treated by spaying the animal and removing the source of the infection. This involves surgically removing both the ovaries and the uterus.  

Surgically removing the entire infected uterus is the preferred treatment for pyometra, but there are possible alternatives that may potentially be used to treat cats that pet parents are planning to breed in the future.  

These alternate treatments are less reliable and carry more risks, but may be an option for breeding cats. One option is administering prostaglandins, a type of hormone, that induce uterine contractions and open the cervix. This may help expel the bacteria and be managed with antibiotics after the procedure.  

Recovery and Management of Pyometra in Cats

Routine spay surgeries typically require very little hospitalization time however, cats who undergo surgery to treat a pyometra are often quite sick. They typically stay in the hospital on IV fluids for a few days following surgery. Recovery time may vary depending on how sick the pet is prior to surgery.  

Following surgery, limit your cat's activity for about 2 weeks to allow time to completely heal. During this time, your cat should not run or jump, and may require being kept in a large crate that has room for her litter box and water bowl.  

You should also regularly check her incision for excessive redness or drainage. To prevent her from licking or chewing at her incision, she may require an E-Collar (plastic or cloth cone). She will likely require oral antibiotics; however your veterinarian may be able to administer a long-acting antibiotic instead. Please be sure to follow your veterinarian’s instructions and do not discontinue her antibiotic before the medication course is completed.   

Pyometra in Cats FAQs

How does pyometra occur?

Pyometra occurs in older, intact female cats that have undergone multiple heat cycles without getting pregnant. It occurs when hormone changes make the uterus more susceptible to bacterial infections. Following these chronic changes, bacteria travels into the uterus from the vulva and replicates, forming pus. This pus makes the pet feel sick as their immune system struggles to fight the bacteria.

When does pyometra occur?

Pyometra most commonly occurs in cats that have had a heat cycle in the past 4 weeks.

What happens if pyometra goes untreated?

If left untreated, a pet with pyometra may become septic as the bacteria travels from the uterus into the bloodstream. This can result in toxic shock, and even death.

Featured Image:

Melissa Boldan, DVM


Melissa Boldan, DVM


Dr. Melissa Boldan graduated from the University of Missouri College of Veterinary Medicine in 2012. She initially practiced mixed animal...

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