Pyometra in Cats: Signs, Surgery Numbers and Costs

An unspayed cat that stops eating and lies flat for two days should be treated as a pyometra case until a vet proves otherwise. If her cervix is closed, a fever and a slightly swollen belly may be the only clues. In a review of 134 surgical cases, 69% arrived dehydrated and 4% already had a ruptured uterus.

Why cats hide this infection better than dogs

Pyometra is a bacterial uterine infection that needs progesterone to start. After ovulation — with or without mating — a cat spends about 40 days in a progesterone-dominated phase called diestrus, while the heat itself lasts only 6–7 days. Progesterone suppresses local immunity, thickens the endometrial glands and keeps the cervix shut: exactly what E. coli needs to multiply in a uterus that is not pregnant.

Timing is the most useful fact an owner can hold onto. Most cats show signs within 4 weeks of their last heat. A Swedish insurance study measured about 17 cases per 10,000 cat-years, a median age of 4 years, a sharp rise after age 7, and 5.7% case fatality — higher than the 3–4% usually quoted for dogs. The dog textbook also misleads here: heavy thirst and urination are common in bitches and uncommon in queens, where poor appetite and lethargy dominate, often mildly.

Open or closed cervix: two different emergencies

Whether pus can drain decides what you see and how fast the cat crashes. Cats groom constantly, so even an open pyometra may leave nothing on the fur: check the bedding she slept on and the skin under her tail.

	Open cervix (patent)	Closed cervix
Discharge	Blood-tinged pus, often the only sign	None
Abdomen	Mildly full; wall may feel thickened	Visibly distended, painful
How sick	Often still eating, mildly dull	Fever, vomiting, collapse in days
Main danger	Diagnosis delayed by good grooming	Toxaemia and uterine rupture

Do not palpate a suspect abdomen yourself. The wall is friable, and pressure can rupture a closed pyometra.

Signs owners actually report

The real list is short and dull, which is why cases drift for days:

• Appetite loss — the commonest complaint, often 24–72 hours ahead of the rest.
• Lethargy — sleeping in odd places, off the usual windowsill.
• Fever — often 39.5–40.5°C, with warm ears and pads.
• Vomiting — intermittent, easily blamed on a hairball.
• Swollen belly — the closed-cervix hallmark.
• Discharge — found on bedding more often than on the cat.
• Weight loss — over a week or two in chronic cases.

Which cats carry more risk

Any entire female is a candidate, including a kitten that has cycled once. Three factors raise the odds:

• Breed. The Sphynx reached 433 cases per 10,000 cat-years in the Swedish data; Siberian, Ocicat, Korat, Siamese, Ragdoll, Maine Coon and Bengal all exceeded 60.
• Hormones. Megestrol acetate above 0.2 mg/kg daily, or medroxyprogesterone above 0.05 mg/kg daily, for over a year, is a documented trigger.
• Never bred. Each empty cycle adds risk; queens that have carried litters are relatively protected.

What the vet does in the first hour

Ultrasound decides it: a thick-walled, fluid-filled tubular uterus, or just wall thickening if the cervix has been open for days. X-rays help less, since early pregnancy and mucometra look alike. Blood work supports rather than proves the diagnosis — a white cell count above 35,000/µL with a left shift is typical, but a normal leukogram does not rule it out. Progesterone above 2 ng/mL confirms an active luteal phase; below 2 ng/mL, medical treatment is far less likely to work.

A guarded swab from the cranial vagina, taken before antibiotics, gives a culture worth acting on. Plain vaginal swabs mostly grow normal flora.

Surgery: the numbers behind "spay her today"

Ovariohysterectomy with the whole cervix removed is the default for any cat not intended for breeding. Most queens are stable enough for anaesthesia after fluids and antibiotics; the unstable ones are stabilised first, because the uterus is friable and the abdomen contaminates easily. Antibiotics usually continue 7–10 days, with monitoring for shock or sepsis for 24–48 hours.

The prognosis beats the emergency framing. In the 134-cat series, every cat that reached surgery survived to discharge (126 of 126; 95% CI 97–100%), though 33% needed at least two nights in hospital.

When medical treatment is defensible

Medical management is for a valuable breeding queen with an open cervix, no sepsis and normal liver and kidney values. It is not a home remedy, and it is unsafe for a closed cervix outside close supervision.

• Aglepristone 15 mg/kg subcutaneously on days 1 and 2, then day 8; it opens the cervix with little contraction, which is why it suits closed cases.
• Dinoprost from 10 µg/kg subcutaneously, escalated slowly, starting day 3 when combined with aglepristone.
• Cabergoline 5 µg/kg orally once daily, most useful within 20 days of ovulation.

One small study cleared 9 of 10 cats with aglepristone plus trimethoprim-sulfadoxine for 7 days, with no recurrence over 2 years. The wider picture is messier: the veterinary manual notes roughly 70% of cats that respond may stay fertile, and recurrence is common. Ultrasound judges response — the uterus should shrink at least 50% within 72–96 hours — and if it does not, surgery is safer.

Cost, and what to do in the next 12 hours

Emergency pyometra surgery often costs more than 10 times a routine spay. A 2024 survey of private practices put the median feline case at $750 (interquartile range $450–$1,000, full range $150–$3,500); high-volume spay-neuter clinics reported $125. The gap is timing, not quality: an elective spay can be scheduled, a pyometra cannot wait for a weekday.

1. Call now and say "entire female, not eating, last heat about three weeks ago". That sentence changes your place in the queue.
2. Note the first day of the last heat and any discharge you saw; both shift the working diagnosis.
3. Do not press the abdomen, and do not use antibiotics left from another pet.
4. Withhold food only if the clinic asks; water is usually fine until admission.
5. Ask whether they can scan today, and what the estimate covers.

This article is for information and does not replace a veterinary examination. Pyometra can kill within 24–48 hours of the first sign, and only a vet who can scan the abdomen can tell open from closed. If your cat is unspayed and unwell, the next step is a same-day appointment — and afterwards, timing the spay is the only permanent prevention.

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