Is pyometra a veterinary emergency?

Yes — pyometra is a life-threatening condition that requires prompt veterinary treatment. Closed pyometra (where the cervix is sealed and pus cannot drain) is particularly dangerous and can cause uterine rupture, peritonitis, and septicaemia within days. Any unspayed female cat showing lethargy, reduced appetite, increased thirst, abdominal distension, or vomiting — particularly in the weeks after a heat cycle — should be seen by a vet the same day. See our when to call the vet guide for the urgency framework.

How is pyometra treated?

The standard treatment is emergency ovariohysterectomy — surgical removal of the uterus and ovaries. This is curative and removes the source of infection. Medical management with prostaglandins and antibiotics is occasionally used in valuable breeding queens where preserving fertility is the priority, but carries a higher risk and significant recurrence rate. Given that spaying eliminates pyometra risk entirely, surgical treatment of the acute episode followed by neutering is the appropriate approach for most pet cats.

Can a spayed cat get pyometra?

Very rarely — a condition called "stump pyometra" can occur if a small amount of uterine tissue was inadvertently left behind during the initial spay surgery. It is uncommon with properly performed surgery. Signs are identical to standard pyometra. If a spayed cat shows signs consistent with pyometra, inform your vet that the cat is spayed — the possibility of stump pyometra should be investigated.

How soon after a heat cycle does pyometra develop?

Pyometra typically develops within 4–8 weeks of a heat (oestrus) cycle. During heat, the cervix opens to allow sperm entry, which also allows bacteria (most commonly Escherichia coli ) to ascend into the uterus. Under progesterone influence in the subsequent luteal phase, uterine defences are suppressed and bacterial proliferation can occur. Repeated cycles increase cumulative risk — older unspayed queens are at highest risk, with the condition most common in cats over 5 years.

Pyometra — Cat Glossary

What it is

Pyometra (from Greek: pyon — pus, metra — uterus) is a bacterial infection of the uterus that causes pus to accumulate within the uterine horns. It is driven by the hormonal environment of the feline reproductive cycle: during and after heat (oestrus), the cervix opens and progesterone levels rise, creating conditions that both permit bacterial entry and suppress uterine immune responses.

The condition is most common in middle-aged to older unspayed queens, though it can occur at any age after the first heat cycle. Each successive reproductive cycle increases cumulative risk. In the UK, pyometra is one of the primary welfare justifications for neutering female cats — see our World Spay Awareness Month page for the broader neutering evidence base.

Open vs closed pyometra

Open pyometra

The cervix remains partially open, allowing pus to drain from the vulva. A visible vaginal discharge — typically white, yellow, or blood-tinged — is present. The cat may be systemically less unwell than with closed pyometra, but the infection is active and still life-threatening without treatment.

Closed pyometra

The cervix is closed; pus cannot drain and accumulates in the uterus. There is no visible discharge, making diagnosis less obvious. The cat deteriorates rapidly as the uterus distends — uterine rupture causing peritonitis is a risk. Closed pyometra is the more immediately life-threatening presentation.

Signs to recognise

Pyometra typically develops 4–8 weeks after a heat cycle. Signs include:

Vaginal discharge (open pyometra) — white, yellow, or blood-tinged
Lethargy and reduced activity
Reduced or absent appetite
Increased thirst and urination (due to bacterial toxins affecting the kidneys)
Abdominal distension — the uterus may be visibly swollen
Vomiting
Fever (or in severe cases, abnormally low temperature indicating septicaemia)

The combination of a recent heat cycle and any of the above signs in an unspayed female cat warrants an immediate vet visit, not watchful waiting. Our when to call the vet guide lists urgency thresholds for all these signs.

Treatment

Emergency ovariohysterectomy (OVH) — surgical removal of the infected uterus and ovaries — is the standard treatment. It is curative and prevents recurrence. Intravenous fluid support and antibiotics are administered pre- and post-operatively to address sepsis and stabilise the cat before anaesthesia.

Surgical risk is elevated in a systemically unwell cat, but the risk of not operating is higher. Most cats recover fully with prompt surgical treatment.

Prevention

Neutering (ovariohysterectomy or ovariectomy) at any age before pyometra occurs eliminates the risk completely. This is one of several well-documented health benefits of spaying female cats — alongside elimination of mammary tumour risk (when spayed before the first heat), prevention of reproductive tract cancers, and removal of the welfare costs of repeated heat cycles. The International Cat Care neutering guidance recommends spaying from 4 months — see our cat vaccinations guide for how neutering timing fits into the first-year health schedule.

What it is

Open vs closed pyometra

Signs to recognise

Treatment

Prevention

Frequently asked questions