Pyometra in dogs and cats

January 3, 2023 - 4 min read
This article is not intended to be a substitute for professional veterinary advice, diagnosis, or treatment. Always seek the advice of your veterinarian with any questions you may have regarding your pet’s care, treatment, or medical conditions.
A dog after surgery

Pyometra is a bacterial infection of the uterus that can happen to any unspayed female dog or cat.

It’s a serious condition that requires immediate vet treatment.

We asked Vet Sophie Bell to tell us more about pyometra, how to spot it, and how to prevent it.

What’s Pyometra in dogs and cats?

Pyometra usually happens around four weeks after your pet’s last season has finished.

Dr. Bell explains:

During this time after oestrus, the hormone progesterone increases the thickness of the uterine wall. Repeated heat cycles without pregnancy can result in cystic areas that secrete fluid. This fluid creates the ideal environment for bacteria to thrive. Your pet’s cervix will also be relaxed during this time, which means bacteria normally found in your pet’s vagina can enter more easily. While the uterine wall is thickened, it’s also harder for the uterus to contract and get rid of any bacteria that has entered.

When your dog or cat is in season, they’re more susceptible to infection.

“During oestrus, the white blood cells that would usually protect your pet from bacterial infections are absent within the uterus," adds Dr. Bell.

"This is so that they don’t damage or kill any sperm, but it also means they can’t kill bacteria at the same time. The bacterial infection creates pus that can make your pet extremely ill as pyometra develops."

Symptoms of Pyometra in dogs and cats

Pyometra is most likely to develop between two and eight weeks after your pet’s last season. Common early symptoms to look out for include:

  • Increased thirst

  • Lack of appetite

  • Fever

  • General malaise

As the pyometra worsens, you may notice your pet’s abdomen becoming bloated. In certain cases, they will also have discharge from their vulva. This can be foul-smelling, bloody, or both.

Pyometra is more common in dogs than in cats. Around one-in-four unneutered female dogs are likely to suffer from the condition by the age of 10.

Female dogs who haven’t been spayed but have never been pregnant are also at higher risk.

Pyometra can often be confused with phantom pregnancy, as some of the symptoms can be similar.

Treatment for Pyometra

Pyometra should always be treated as a medical emergency. If you spot any potential symptoms in your dog or cat, you should contact your vet immediately. It’s worth keeping a note of when your dog was last in season, too, as this can be useful information for your vet.

“The only way to accurately diagnose pyometra is with an ultrasound scan,” says Dr. Bell. “Your vet may also recommend blood tests, fluid therapy, and medication to stabilize your pet prior to surgery.”

X-ray of pyometra

Pyometra cases fall into two categories:

  • Open pyometra occurs when your pet’s cervix is open. Any pus forming within the uterus can drain out through the vagina.

  • Closed pyometra occurs when your pet’s cervix remains closed. Pus and fluid within the uterus cannot drain out and could cause your pet’s uterus to rupture.

The most common treatment for pyometra is immediate spaying. “Operating on a closed pyometra is extremely time-critical,” says Dr. Bell.

This is because the fluid filling your pet’s uterus could build up to the point where their uterus ruptures or the bacteria starts to infect their bloodstream. Without prompt treatment, both of these scenarios can be life-threatening.

If your pet has an open pyometra with pus draining from their vulva, spaying is also usually the recommended course of action. But what if your cat or dog is used for breeding and you’d like them to have more litters in the future?

“In some rare cases, pyometra can be treated with antibiotics and hormones, but the risk of the pyometra recurring in the future is high. The pros and cons of this option will need to be carefully discussed in detail with your vet,” says Dr. Bell.

In some rare cases, pyometra can be treated with antibiotics and hormones, but the risk of the pyometra recurring in the future is high.

It’s also worth noting that spaying a pet with pyometra is more complicated than a routine spay, so it can result in a more lengthy and expensive procedure. If your pet needs emergency, out-of-hours care, then the costs will be even higher.

Although spaying isn’t generally covered by pet insurance, it may be if it’s to treat pyometra.

“Spaying may be covered by pet insurance as long as it's not pre-existing and the spay was recommended by a vet as part of a treatment plan,” says ManyPets’ technical claims manager, Sarah Dawson.

Spaying won’t always be covered. Your vet might recommend a different course of treatment, like medication, and then the spay would be classified as preventative and wouldn’t be covered, just as regular spaying isn’t. If your dog’s had a milder pyometra in the past, it could be excluded as a pre-existing condition, depending on the type of policy you have and when you took it out.

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Pre-existing conditions and insurance - how does it work?

ManyPets has exclusions for pre-existing conditions, but past conditions don’t always prevent future coverage. Get the details.

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Pyometra recovery for dogs and cats

When your furry friend undergoes pyometra surgery, you’ll want to ensure they have the smoothest recovery possible. While the tips below can help, every pet is unique, so always follow your veterinarian's specific advice for your pet's post-surgery care.

Pyometra recovery for dogs

For our canine companions, the American College of Veterinary Surgeons advises that post-surgery care is quite straightforward, akin to what's needed after a routine spay. One key aspect to note is that your dog may need to be on antibiotics for a minimum of ten days.

During the initial two weeks post-surgery, it’s crucial to keep their activity levels low. This means no energetic play, avoiding stairs, and keeping them on a leash to prevent any strain on the surgical site.

Pyometra recovery for cats

As for our feline friends, while specific recovery times vary, the guiding principle remains the same: rest and careful monitoring. The recovery process for cats might differ based on how severe the pyometra was before surgery.

Generally, post-operative care includes limiting their physical activity for a few weeks and following any medication regimen prescribed by your vet. Keeping a close eye on your cat's behavior and comfort level during this period is essential.

How to prevent your dog or cat from developing Pyometra

The best way to prevent pyometra is to get your female dog or cat spayed.

Spaying is a routine surgery to remove your pet’s uterus and ovaries. As a result, they’ll never suffer from the dangers of pyometra.

Your vet will be able to recommend the best age to carry out this routine operation, as well as the optimal time in your dog’s heat cycle to have the procedure.


Emma has written extensively about the environment and health but she has a real passion for pets. She has written articles for The Happy Cat Site, Pet Life Today and Dogsnet, as well as ManyPets.