When to see a vet urgently
Contact a vet immediately if an unspayed female develops any of the following:
- Pus or bloody discharge from the vulva.
- Unusual lethargy, failure to eat or vomiting.
- An enlarged or painful abdomen.
- Collapse or very pale gums or other mucous membranes.
No discharge does not rule out pyometra. Find a vet near you.
Overview
After ovulation, usually triggered by mating in cats but also possible without it, progesterone is released following oestrus. It changes the uterine lining, making it susceptible to bacterial infection. Pyometra develops if pus accumulates. There are two forms:
- open, with pus draining through the vagina;
- closed, with the cervix shut and pus trapped inside, which is particularly dangerous and may lead to uterine rupture.
An open form does not mean a harmless infection. Even if some discharge escapes, infection remaining in the uterus can affect the whole body. Cats also often lick discharge away, so an open pyometra may not produce obvious discharge for you to notice.
Progesterone normally supports pregnancy but can also reduce uterine contractions and increase secretions from glands in the lining. In favourable conditions, bacteria ascending from around the vagina start multiplying in the uterus. Bacterial presence alone therefore does not explain disease without considering uterine conditions.
Causes
- hormonal disturbances involving prolonged progesterone effects;
- repeated seasons without pregnancy;
- hormonal products used to suppress oestrus;
- bacterial infections, most often Escherichia coli;
- age-related uterine lining changes.
However, not every season without pregnancy leads to pyometra. In cats, ovulation and the progesterone phase afterwards are particularly important. An unmated indoor cat can be affected because ovulation can occur without mating. Pregnancy is not used as preventive treatment for pyometra.
Cystic thickening of the uterine lining and pyometra often occur together, but not always. Young cats can also develop pyometra without long-standing degenerative changes. Age alone therefore cannot rule it out.
Risk factors
- Unspayed females over 5–6 years.
- Cats given products to suppress seasons.
- Cats that have never been pregnant.
- Repeated false pregnancies.
The age threshold is not absolute: a young, sexually mature female can also be affected. The list describes risk factors, and previous pregnancy does not guarantee protection. Mention earlier hormonal products even if no longer used. Do not wait to monitor a cat with symptoms simply because one listed factor does not apply.
Typical symptoms
- pus or bloody vaginal discharge in the open form;
- no discharge but rapid deterioration in the closed form;
- thirst and more frequent urination;
- failure to eat, lethargy and listlessness;
- fever and vomiting;
- an enlarged abdomen as pus accumulates;
- with the closed form, sudden collapse, uterine rupture and peritonitis.
Early changes may be limited to slight discharge or eating less. Discharge may appear beneath the tail, on bedding or where the cat has sat. Tell the vet even if your cat cleans the coat and sometimes seems brighter.
Increased drinking and urination may relate to bacterial substances affecting kidney function. This is not specific to pyometra and also occurs in other diseases. Not every cat has every listed sign, and the absence of fever or obvious abdominal swelling does not establish safety.
Complications and consequences
- sepsis, often called blood poisoning;
- peritonitis following uterine rupture;
- damage to multiple organs;
- death without urgent care.
In sepsis, the inflammatory response disrupts body function. Circulation, kidneys and other organs can be damaged, while rupture spreads infection into the abdomen. This risk of progression determines urgency: the cat is examined before collapse, rather than only afterwards.
Diagnosis at the vet
- history and clinical examination;
- a complete blood count and blood biochemistry to assess increased white cells, inflammation and systemic toxic effects;
- uterine ultrasound to identify enlarged, fluid-filled horns;
- X-rays when there is a large amount of pus;
- bacterial examination of discharge.
What do investigations establish?
Mention the last observed season, possible mating, previous pregnancies and hormonal medicines. Spaying records also matter. The vet assesses general condition, hydration and circulation while investigating the cause. Supportive care for a seriously ill patient can begin alongside tests.
Pyometra in an already spayed cat is rare but possible in particular circumstances: remaining uterine tissue can become infected if functional ovarian tissue or an external hormonal influence is present. Returning seasons or abnormal discharge after surgery therefore warrant examination.
Blood tests assess kidney function and other disturbances as well as inflammation. White blood cells may increase with inflammation but can also fall in severe disease. Urine testing can help assess concentration. One blood value alone cannot confirm or exclude pyometra.
Ultrasound assesses uterine size, wall and contents and possible abdominal changes. It can also distinguish inflammation from normal pregnancy. X-rays may show an enlarged uterus but cannot reliably establish the cause of its contents alone. In the open form, enlargement may not be obvious radiographically.
Discharge cytology may show inflammatory cells, and bacterial culture helps select medicines. However, treatment of a seriously ill cat is not delayed while waiting for culture. Findings are interpreted alongside symptoms and imaging because similar discharge can occur with other reproductive diseases.
Treatment
The usual treatment removes the infected uterus and ovaries. Intravenous fluids, antimicrobials and other support may be needed before anaesthesia. Stabilisation means supporting circulation and vital functions so surgery can be as safe as possible. It does not mean staying home to wait for infection to settle.
Surgery in a sick cat differs from planned spaying of a healthy animal. The uterus may be large and fragile, and leakage of infected contents into the abdomen is avoided. Afterwards, condition, fluid balance, pain and possible sepsis effects are monitored. Antibiotics alone do not reliably remove infected material accumulated in the uterus.
Medical treatment may be considered for a carefully selected breeding cat in good condition under a vet experienced in reproduction. It aims to alter progesterone effects and empty the uterus while treating bacterial infection. Preserving fertility medically is not an appropriate first priority with sepsis or peritonitis. Response is monitored through examinations and ultrasound, and surgery may still become necessary.
Discharge and prognosis
Going home depends on condition and treatment. Ask for written medicine, feeding, wound protection and follow-up instructions. Monitor eating, drinking, urination and alertness. Contact the treating vet if your cat weakens, vomits again or shows concerning behavioural changes. Deterioration is not automatically attributed to lingering anaesthetic effects.
Keep your recovering cat indoors and restrict jumping as instructed. Keep the wound dry and do not apply your own cleansers or treatments. Prevent licking with the advised protection. Wound opening, persistent discharge, increasing swelling or an unpleasant smell warrants contact.
The outlook is often good when the infected uterus is removed and the cat responds to supportive care. Severe sepsis, rupture and organ damage worsen prognosis. Infection can recur after medical treatment, and later pregnancy is not guaranteed. Continued breeding and eventual surgery require a separate plan.
Prevention
- The most effective prevention is spaying before the first season or soon afterwards.
- Avoid hormonal products to suppress seasons.
- Take older unspayed females for regular veterinary checks.
- Monitor closely in the weeks after a season.
Spaying timing is agreed according to the cat's situation. If breeding continues, regular checks do not remove pyometra risk or replace investigating acute signs. Do not give hormones altering oestrus yourself.
Important for cat owners
Pyometra is life-threatening and needs an immediate veterinary or emergency visit. Medical treatment is usually poorly effective, and the standard treatment is surgical removal of the uterus and ovaries, called ovariohysterectomy. The earlier surgery takes place, the better the recovery chances.
Nevertheless, medical treatment is not ineffective in every cat: carefully selected breeding cats can respond successfully. Selection, monitoring and changing treatment are the vet's responsibility. This is not an option to try at home instead of urgent assessment.
This article provides general information and does not replace veterinary care. If you notice signs of illness in your cat, contact a vet.
Frequently asked questions
Can a cat have pyometra without discharge?
Yes. The closed form prevents discharge from escaping, and a cat may lick it away even with the open form. No discharge does not rule out the disease.
Can a young or unmated cat be affected?
Yes. Ovulation can occur without mating, and pyometra is also diagnosed in young cats. Deteriorating general health needs investigation regardless of age.
Are antibiotics enough to treat pyometra?
Usually not alone. Infected uterine contents need removal, most often surgically. Medical treatment is a closely monitored option for selected patients.
Can a cat recover after pyometra surgery?
Many recover well with timely treatment. Sepsis, rupture and organ damage particularly worsen prognosis, so do not delay seeking care.
This article is for general information only and is not a guide to treatment. If you notice the first signs of illness, contact your vet.
Paw4care editorial team
Sources
- Pyometra, American College of Veterinary Surgeons, accessed 2026-11-03.
- Reproductive Disorders of Female Cats, Merck Veterinary Manual, accessed 2026-11-03.
- Pyometra in Cats, VCA Animal Hospitals, accessed 2026-11-03.
- Cystic Endometrial Hyperplasia–Pyometra Complex in Small Animals, Merck Veterinary Manual, accessed 2026-11-03.
- Initial Triage and Resuscitation of Small Animal Emergency Patients, Merck Veterinary Manual, accessed 2026-11-03.
- Care of Surgical Incisions in Cats, VCA Animal Hospitals, accessed 2026-11-03.
- 2020 AAHA Anaesthesia and Monitoring Guidelines: Phase 3 Return Home, AAHA, accessed 2026-11-03.
- Diagnosis and medical treatment of pyometra in the queen, Clinical Theriogenology, accessed 2026-11-03.