Pyometra in Cats

Overview

Pyometra is a serious uterine infection that affects unspayed female cats. It's a true medical and surgical emergency — but with the very good news that treated promptly, survival rates are genuinely high.

• Affects only unspayed female cats
• Less common in cats than in dogs, but progresses quickly and requires urgent care when it occurs
• Two forms: open (cervix open, discharge visible — easier to detect) and closed (cervix closed, no visible discharge — more dangerous because it's harder to catch early and pressure builds internally)
• 100% preventable through spaying

Common Symptoms

Early / Easy-to-Miss Signs

• Lethargy
• Reduced appetite
• Increased thirst

Advanced Signs

• Vaginal discharge (in open pyometra) — may be pus-like or bloody
• Abdominal swelling or distension
• Vomiting
• Fever

Cats often hide illness well, and vaginal discharge (if present) can be easy to miss since cats groom themselves fastidiously — this is part of why pyometra is sometimes caught later in cats than in dogs.

Possible Causes

• Develops from cystic endometrial hyperplasia (CEH) — with each heat cycle, hormonal changes thicken the uterine lining, creating conditions where bacterial infection (most often E. coli) can take hold
• Risk increases with age — most common in cats over 5 years old, though it can occur earlier
• Some genetic predisposition has been noted in certain breeds, including Sphynx, Siamese, Ragdoll, and Bengal
• Cats previously given estrogen/progesterone-containing medications are also at higher risk

Diagnosis

• Physical exam and history (unspayed status is the key clue)
• Bloodwork and urinalysis
• Abdominal ultrasound — the best diagnostic tool, confirms a fluid-filled, infected uterus and helps assess severity
• X-rays may be used as well, though ultrasound is generally preferred for this diagnosis

Treatment

• Emergency surgery (ovariohysterectomy / spay) is the gold-standard, most effective treatment
• Pre-surgical stabilization (IV fluids, addressing sepsis/dehydration) is often needed given how sick these cats can be by the time of diagnosis
• Surgery should not be delayed once diagnosed — the risk of uterine rupture and life-threatening sepsis continues as long as the infected uterus remains
• Medical management alone (without surgery) exists for select open-pyometra cases but is less reliable and carries a real risk of the condition recurring at the next heat cycle

Nutrition & Food Intake

• Not a primary factor in this condition — the priority is surgical treatment
• Post-surgical recovery typically involves a normal diet resuming within a day or two, per your vet's guidance
• Cats recovering from major surgery may have reduced appetite for a short period, which is normal but should be monitored

Home Physical Checks (What to Look For Yourself)

• Vaginal discharge – any unusual discharge in an unspayed female cat warrants immediate veterinary attention
• Abdomen – note any new swelling or distension
• Water and food intake – increased thirst combined with reduced appetite is a pattern worth taking seriously
• Energy levels – new lethargy in an unspayed female cat, especially one recently in heat, should prompt a vet visit

Supportive Supplements (General Info — Not a Prescription)

• No supplement treats or prevents pyometra — this condition requires surgical intervention
• The only reliable prevention is spaying, which eliminates the risk entirely

When to Seek Emergency Care

This condition is always an emergency once suspected. Seek immediate veterinary care if an unspayed female cat shows:

• Any vaginal discharge
• Abdominal swelling
• Lethargy combined with reduced appetite and increased thirst
• Vomiting or fever

Do not wait to see if symptoms resolve on their own — the infected uterus can rupture, which significantly worsens the prognosis.

Prevention

• Spaying is 100% preventive — once a cat is spayed, pyometra cannot occur
• Early spay (commonly recommended around 5-6 months old) is both safer and more affordable than treating pyometra later
• If you're caring for unspayed rescue cats, prioritizing spay surgery is one of the most impactful health decisions you can make for them

Prognosis

This is genuinely one of the more hopeful emergencies on this list when treated promptly:

• Multiple veterinary studies report survival to hospital discharge with surgery in the range of 90-100%, with one large study of 134 cats reporting 100% survival to discharge among those who underwent surgery, and an overall mortality around 4%
• Fatality rates across various studies range from about 3% to 8% in most reports, though this rises significantly if the uterus has ruptured before treatment — 30-50% mortality has been reported in ruptured cases
• The clearest message: pyometra caught and treated before rupture has an excellent prognosis; the danger comes specifically from delay

Sources: Journal of the American Veterinary Medical Association (2022 pyometra outcomes study); EveryCat Health Foundation; American College of Veterinary Surgeons; PetMD.