Pyometra Prevention

Written By Kathleen Lee

written by Dr. Jessica Titchenal

What Every Pet Owner Should Know about Pyometra

Pyometra is one of the most serious health risks faced by unspayed female pets—both dogs and cats. This infection of the uterus can progress quickly, become life-threatening, and often requires emergency surgery.

The good news? Pyometra is completely preventable through spaying.

Spaying (removal of the ovaries and uterus) eliminates the risk of pyometra and provides long-term health benefits for many pets.

Understanding Pyometra: What Is It?

Pyometra is a severe bacterial infection of the uterus that develops in unspayed female pets.

While it may sound like a simple infection, pyometra is a medical emergency. The uterus becomes enlarged and fills with infected material (pus), while toxins produced by the infection can spread throughout the body.

Without treatment, pyometra can lead to:

  • Sepsis (body-wide infection)

  • Kidney injury

  • Organ dysfunction or failure

  • Shock

  • Death

Because pets often hide illness well, signs may not become obvious until the disease is advanced.

Symptoms of Pyometra

Signs can vary and may initially be subtle. Common symptoms include:

  • Decreased appetite

  • Lethargy or weakness

  • Increased thirst and urination

  • Vomiting and/or diarrhea

  • Fever

  • Weight changes

  • Dehydration

  • Distended or painful abdomen

  • Increased heart rate

  • Increased breathing rate

  • Unkempt haircoat

  • Vaginal discharge (bloody, cloudy, or pus-like)

It’s important not to rule out pyometra simply because you don’t see discharge—especially in cats, who often groom frequently, or in cases where the cervix remains closed.

Open vs. Closed Pyometra

Open Pyometra

When the cervix remains open, infected material can drain from the uterus.

Signs may include:

  • Vaginal discharge

  • Fever

  • Reduced appetite

  • Low energy

  • Increased sleeping or hiding

Because some infected material can drain, pets may appear less ill early on—but treatment is still urgent.

Closed Pyometra

With closed pyometra, the cervix remains sealed and infected material becomes trapped inside the uterus.

This form often progresses more rapidly and can become critical in a short period of time.

Signs may include:

  • Enlarged abdomen

  • Severe lethargy

  • Refusal to eat

  • Vomiting

  • Diarrhea

  • Rapid decline in condition

Closed pyometra is especially dangerous because there may be no visible discharge.

How Does Pyometra Happen?

Pyometra develops because of hormonal changes associated with repeated heat cycles.

Each time an unspayed pet goes through a heat cycle, the uterus prepares for pregnancy. Hormones—particularly progesterone—cause the uterine lining to thicken and create conditions that support pregnancy.

When pregnancy does not occur, those hormonal effects may not fully reset over time.

It’s also important to know that pyometra risk does not appear to be the same across all dogs. Research suggests certain breeds may have a higher lifetime risk of developing pyometra than others, which points toward a possible genetic component in addition to hormonal influences. Dog breeds identified as having increased risk in some studies included Leonbergers, Irish Wolfhounds, Bernese Mountain Dogs, Great Danes, Staffordshire Bull Terriers, Rottweilers, Dobermans, Golden Retrievers, and several spaniel breeds. Cat breeds identified as having increased risk in some studies included Siberian cat, Ocicat, Korat, Siamese, Ragdoll, Maine Coon, Bengal and Sphynx. However, pyometra can occur in any unspayed female pet regardless of breed.

While breed may influence risk, the strongest modifiable factor we know remains reproductive status—spaying eliminates the risk of pyometra entirely because the uterus is removed.

Repeated heat cycles can lead to:

  • Thickening of the uterine lining

  • Formation of cystic changes within the uterus

  • Reduced ability of the uterus to clear fluid and bacteria

  • An environment where bacteria can grow

Bacteria that normally live within the reproductive tract may then enter and multiply inside the uterus, resulting in infection.

Certain hormone-containing medications (particularly those containing progesterone or estrogen) may also increase the risk of pyometra.

Diagnosis: How Do We Diagnose Pyometra?

If pyometra is suspected, your veterinarian will perform an exam and recommend diagnostic testing.

Testing may include:

  • Bloodwork to evaluate infection, hydration, and organ function

  • Urinalysis to assess kidney health

  • X-rays to evaluate for uterine enlargement

  • Ultrasound to confirm fluid within the uterus and help rule out other causes

Diagnostics do more than confirm the diagnosis—they help us understand how advanced the infection is, evaluate how your pet’s body is responding, and create the safest treatment plan possible.

Testing gives us answers and helps give your pet the best chance at a healthy recovery.

Treatment: How Is Pyometra Treated?

Pyometra is most commonly treated with emergency surgery to remove the infected uterus and ovaries (an emergency spay).

Because many pets with pyometra are already sick by the time they arrive, treatment often includes:

  • IV fluids

  • Pain control

  • Antibiotics

  • Bloodwork monitoring

  • Hospitalization and supportive care

The earlier treatment begins, the better the chances of recovery.

While medical management may be considered in select breeding animals under specific circumstances, surgery remains the safest and most effective treatment for most pets.

Why Spaying Matters

Spaying is one of the most effective ways to protect your pet’s long-term health.

In addition to preventing unwanted litters, spaying completely eliminates the risk of pyometra and may reduce the risk of other reproductive diseases.

Our goal is never to pressure decisions—but to make sure you have the information you need to make thoughtful, informed choices for your pet.

Ready to Talk About Spaying?

If you have questions about spaying, timing, recovery, or whether preventive surgery is the right fit for your pet, we’re here to help.

Call Cheney Veterinary Clinic at (509) 235-6860 to schedule an appointment with one of our veterinarians. We’d love to talk through your pet’s lifestyle, health, and your goals so we can make a plan together.

RESOURCES

Jitpean S, Hagman R, Ström Holst B, Höglund OV, Pettersson A, Egenvall A. Breed variations in the incidence of pyometra and mammary tumours in Swedish dogs. Reprod Domest Anim. 2012 Dec;47 Suppl 6:347-50. doi: 10.1111/rda.12103. PMID: 23279535.

Wallace, Grayson & Casal, Margret. A review of pyometra in small animal medicine: incidence, pathophysiology, clinical diagnosis, and medical management. Clinical Theriogenology. 2018; 10. 435-452. 10.58292/ct.v10.9901.

Kathleen Lee