Pyometra in Cats: A Life-Threatening Infection in Unspayed Females

By Tailwisp Editorial TeamUpdated October 20, 20264 min read

Few emergencies are as preventable, or as dangerous, as pyometra. In an unspayed female, hormonal changes can make the uterus a perfect place for bacteria to grow. Without treatment, the infection spreads, and the cat can die from sepsis or a ruptured uterus.

What happens

After a heat cycle, progesterone prepares the uterus for pregnancy. If the cat does not become pregnant, repeated cycles can cause the uterine lining to thicken and form cysts, a condition called cystic endometrial hyperplasia. In this environment, bacteria that enter through the cervix, often E. coli, multiply. The uterus fills with pus. The toxins affect the kidneys and the rest of the body.

Open and closed pyometra

• Open pyometra. The cervix is open, so pus drains out through the vagina as a thick, smelly, yellow, green or bloody discharge. Owners usually notice the discharge, and cats may appear less sick, though still seriously ill.
• Closed pyometra. The cervix is shut, and pus builds up inside. There may be no discharge, so the first signs are lethargy, a swollen belly and collapse. This form is more dangerous, since the uterus can rupture.

Signs

• Lethargy, weakness and hiding.
• Loss of appetite.
• Excessive thirst and urination. See why is my cat drinking so much water.
• Vomiting or diarrhea.
• A swollen or painful belly.
• Fever, or a low temperature in advanced cases.
• Vaginal discharge, and licking of the area.
• Rapid breathing, pale gums and collapse.

Signs often appear two to eight weeks after a heat. See cat emergency warning signs.

Diagnosis

The vet examines the cat, and uses bloodwork, which may show a high white cell count and kidney changes, and an ultrasound or X-ray to show an enlarged, fluid-filled uterus. A vaginal swab may help in open cases.

Treatment

• Emergency surgery. An ovariohysterectomy, removing the infected uterus and ovaries, is the standard and safest treatment. It cures the problem and prevents recurrence. Before and after surgery, the cat receives intravenous fluids, antibiotics and pain relief, and is monitored closely.
• Medical treatment. In rare cases, such as valuable breeding cats that are stable, vets may try drugs to open the cervix and expel pus, with antibiotics. Success is not guaranteed, and the infection often returns. It is not recommended for cats that are very sick.

Surgery is riskier in a sick cat than in a healthy one, which is why prevention is far better. See cat anesthesia safety.

Recovery

Most cats treated promptly recover well. Keep your cat quiet, give medicines, use a cone, watch the incision and return for rechecks. See caring for a cat after spay or neuter. Cats with kidney damage may need ongoing care.

Prevention

Spaying removes the uterus and ovaries, and eliminates the risk of pyometra, as well as unwanted litters, heat behaviors and most mammary cancer risk. See when to spay or neuter a kitten and mammary cancer in cats. If you do not plan to breed, ask your vet about the right time.

Hormone shots

Progestin injections used to prevent heat raise pyometra risk and are generally not advised. Discuss safer options with your vet.

Heat cycles in cats

Unspayed female cats may come into heat every few weeks during the breeding season, with behaviors such as loud calling, rolling, rubbing, raising the rear and trying to escape. Cats that do not mate keep cycling, and each cycle exposes the uterus to progesterone. Over time, this raises the risk of uterine disease. Many owners mistake heat for pain or illness. If your cat shows these signs, talk to your vet about spaying.

Why early signs are missed

Cats hide illness, and the early signs of pyometra, such as mild lethargy and a lower appetite, can be easy to overlook. Increased thirst may be hard to notice, and a closed pyometra gives no discharge. Keep an eye on an unspayed female in the weeks after a heat, and call the vet at the first sign of change. Quick action saves lives.

Costs of emergency versus planned surgery

Emergency spay for pyometra costs more than a routine spay, because of hospitalization, fluids, bloodwork and intensive monitoring. It is also riskier. A routine spay in a healthy young cat is far cheaper and safer. If cost is a worry, look for low-cost clinics. See low-cost vet care for cats and cat vet visit costs.

Stump pyometra

Rarely, a cat that has been spayed can develop an infection in a small piece of uterine tissue left behind, called stump pyometra, particularly if hormones are present. If a spayed cat has signs such as discharge or lethargy, with a history of heat behavior or hormone use, see a vet.

Healing and follow-up

After surgery, expect a hospital stay of a day or two, and a recovery of about two weeks at home. Return for suture removal and recheck bloodwork if your cat had kidney changes. Most cats go on to live normal lives.

When to see a vet

See a vet immediately if an unspayed female cat is lethargic, drinking a lot or has a discharge. Use the US vet directory to find a clinic.

This article is general educational information, not veterinary advice. Every cat is different. If your cat is unwell, or you are unsure about a symptom, diet change or medication, contact your veterinarian.