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What Is Pyometra in Cats?

Reviewed by Amy Flowers, DVM on December 26, 2021

Pyometra is a bacterial infection in your cat's uterus. It's a potentially fatal infection that requires urgent medical treatment. The uterus of cats who have pyometra is filled with pus. Pyometra can occur in any cat who hasn't been spayed, but it's more common in older cats. It usually occurs in cats who have been in heat in the past month.

What Causes Pyometra in Cats?

Pyometra is caused by bacteria entering your cat's uterus. Normally, the cervix is closed, which helps prevent bacteria from getting into the uterus. However, when your cat goes into heat, the cervix relaxes to let in sperm. Her body also releases the hormone progesterone. This hormone causes the lining of her uterus to thicken to get ready for pregnancy.

If your cat doesn't get pregnant after several cycles, the lining of her uterus may continue to thicken. These conditions make it easier for cysts to form. This thick, cystic lining secretes fluid that allows bacteria to grow. Your cat's immune system would normally release white blood cells to fight bacteria. However, during heat, white blood cells are suppressed from going into the uterus so that sperm won't be damaged by them.

High progesterone levels also prevent the muscles in the wall of the uterus from contracting. These contractions would normally help the uterus get rid of extra fluid and bacteria. If your cat is taking hormones for any condition, they can also cause these changes that can lead to pyometra.

What Are the Symptoms of Pyometra in Cats?

The symptoms of feline pyometra can vary from cat to cat. Some cats may seem very ill while some may just have pus in their vaginal discharge. Any cat who hasn't been spayed and is ill should be checked for pyometra. Some of the more common symptoms include: 

  • Not eating
  • Urinating a lot
  • Drinking a lot
  • Lethargy
  • Depression
  • Bloody discharge from the vagina

Some symptoms that aren't as common include: 

  • Vomiting
  • Diarrhea
  • Weight loss
  • Inflamed eyes
  • Swollen abdomen

How is Pyometra in Cats Diagnosed?

If your cat's cervix is open and she has a discharge with pus in it, that may be enough for your vet to diagnose pyometra. If your cat's cervix is closed, there may not be a discharge, so the vet may need to do more tests. Some tests that your vet may do are:  

  • General chemistry profile, which is a blood test that gives your vet general information about how your cat’s organs are functioning 
  • Complete blood count, which tests the cells that make up your cat’s blood
  • Urinalysis
  • Abdominal X-rays
  • Abdominal ultrasound

What Is the Treatment for Pyometra in Cats?

Because pyometra is a serious, life-threatening condition, your cat will need immediate treatment. Pyometra is normally treated by surgically removing the uterus and ovaries. This surgery is called an ovariohysterectomy and is the same surgery that's done to spay cats. The surgery is more complicated in cats with pyometra because they are already ill.

If your cat is diagnosed early, the surgery will be easier than if she is diagnosed when she is very ill. Cats who are already severely sick with pyometra will usually have to be stabilized before the vet can operate on them. They may need to be given intravenous (IV) fluids before and after surgery. They may also have to stay in the hospital longer. After surgery, your cat may be given antibiotics for two weeks.

If you want to breed your cat, pyometra can be treated without surgery. However, this type of treatment is not as effective, has significant risks, and can cause long-term complications for your cat. Medical treatment for pyometra involves giving your cat prostaglandins. These are hormones that lower the level of progesterone in your cat's blood, cause the uterus to contract, and open the cervix. When the uterus contracts and the cervix is open, your cat's body can get rid of the fluid and pus.

This treatment usually takes about 48 hours to start working, so if your cat is very ill it's not a good option. Your cat may also develop pyometra again later if she doesn't have an ovariohysterectomy. Additionally, the prostaglandins can cause side effects such as: 

  • Restlessness
  • Panting
  • Vomiting
  • Defecation
  • Excessive saliva
  • Abdominal pain

Prostaglandins can also cause a life-threatening condition called peritonitis in cats with pyometra. Peritonitis occurs when the uterus ruptures and pus spills out into the abdominal cavity. Peritonitis is more likely to occur if your cat's cervix is closed.

How Long Can a Cat Live With Pyometra?

The chances of a cat surviving pyometra without treatment are very low. There are no home remedies for pyometra in cats. Without prompt treatment, the bacterial infection will usually kill a cat. If the cat's cervix is closed, the buildup of pus may cause her uterus to rupture, which may also be fatal.

Can Pyometra in Cats Be Prevented?

The best way to prevent pyometra is to have your cat spayed when she is young. Cats who have been spayed rarely develop pyometra. However, it is possible for a cat who has had an incomplete ovariohysterectomy to develop pyometra if part of the uterus is left in her body. This is more likely to happen if the cat has been taking hormones.

Show Sources

SOURCES:

American College of Veterinary Surgeons: "Pyometra."

VCA Hospitals: "Pyometra in Cats."

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