Metritis in Queens: The First 72 Hours After Birth

Foul-smelling discharge plus a fever over 39.5°C in the first 72 hours after birth is metritis until proven otherwise, and it is an emergency: a queen can go from dull to septic in under 24 hours. Pyometra looks similar but arrives at a different time — one to eight weeks after a heat, in a queen that is not pregnant — and for a closed pyometra the treatment is surgery, not antibiotics. Timing decides which one you are dealing with.

Two conditions, one uterus, different clocks

Metritis is bacterial infection of the uterine lining that follows a birth. Bacteria enter through the open cervix during a difficult delivery, a retained kitten or placenta, or unsterile assistance. Signs start 24–72 hours postpartum, exactly when a normal queen is still passing lochia — the reddish-brown, essentially odorless discharge that can last 1–3 weeks after delivery.

Pyometra is a hormonal disease, not a birth complication. After ovulation the corpus luteum secretes progesterone for roughly 60–70 days in the cat, even without pregnancy, and progesterone both closes the cervix and suppresses the white cells that would normally clear bacteria. The uterus fills with fluid and pus, typically 1–8 weeks after a heat. Because cats ovulate by reflex, a queen that was never mated can still develop it. Risk rises in queens over 4 years, and the cat age chart converts her birthday into the human-equivalent number vets use when weighing surgery risk.

The 24–72 hour window after birth

Check the queen at 6, 24, 48 and 72 hours: temperature, appetite, milk, and the pad under her. Normal refers to a temperature of 38.1–39.2°C, a queen who eats within 12 hours of the last kitten, and a discharge that is red-brown and smells like iron, not like rot. Anything that smells foul, or is grey-green or blood-tinged with clots after day 3, needs a same-day visit.

Kittens are the earliest readout. A litter that was gaining 10–15 g a day and stops gaining, or cries and roots constantly at 3–4 days, is often reporting on milk from an inflamed uterus rather than on its own health. Weigh them daily on a 1 g scale; a loss of more than 10% of birth weight in 24 hours is a hand-feeding decision, not a wait-and-see.

What the fever and the bloodwork tell you

A temperature above 39.5°C with a foul discharge is enough to start treatment. Below that line, the queen may still be sick: a septic queen can be hypothermic under 37.5°C with pale gums and a heart rate over 220 beats per minute, and that is the more dangerous presentation. Take it twice a day for five days after a difficult birth; one reading hides the trend.

Bloodwork separates the stable from the critical. Expect a neutrophilia with a left shift and toxic change in metritis, and in pyometra the same picture plus monocytosis, hyperglobulinemia, and often azotemia from dehydration or from a uterus pressing on the ureters. A packed cell volume over 50% or glucose over 250 mg/dL means the queen is dehydrated and stressed enough to need intravenous fluids before anything else. None of these numbers diagnose the condition alone — they grade how sick she is.

Ultrasound is the tiebreaker

In a cat, ultrasound shows what a radiograph cannot: fluid, wall thickness, tension in the horns. In a 4 kg queen, a uterine body measuring under 5 mm and horns under 6–7 mm with no fluid is unremarkable. Fluid-filled, tubular horns with a thin wall fit acute metritis; thick, irregular walls with swirling echogenic content and cystic areas fit pyometra. Ask for the measurement in millimeters on the report, not just the word enlarged, so you can compare at the 48-hour recheck.

Feature	Metritis	Pyometra
When it starts	24–72 hours after birth	1–8 weeks after a heat
Discharge	Foul, grey-green or bloody, always present	Purulent if the cervix is open; none if closed
Temperature	Often above 39.5°C	39.5–40.5°C, normal, or low in sepsis
Bloodwork	Neutrophilia with left shift	Neutrophilia, monocytosis, high globulin, azotemia
Ultrasound	Fluid, thin walls, both horns enlarged	Fluid, thick irregular walls, cystic areas
First choice	Antibiotics plus uterine evacuation	Surgery, unless she must be bred again

Conservative treatment, and its limits

Metritis in a queen who is eating, alert, and below 39.5°C can be treated medically: a broad-spectrum antibiotic active against the mixed gut flora that cause it (amoxicillin-clavulanate at 12.5–25 mg/kg every 12 hours is common), oxytocin at 0.5–3 IU intramuscularly every 6–12 hours for up to 3 doses to help the uterus empty, and fluid support if she is dehydrated. Expect the smell and fever to improve in 24–48 hours; if not, the plan changes.

In an open pyometra in a valuable queen, prostaglandin therapy can empty the uterus and preserve fertility, but it is uncomfortable, requires repeated handling, and carries a real risk of rupture if the cervix closes mid-treatment. Most referral clinics reserve it for a queen under 6 years with an open cervix, normal kidney values, and an owner who accepts a 48-hour hospitalization. Everything else goes to surgery.

The decision line for surgery

Surgery is the answer when any of these is true:

• Closed cervix with a distended uterus on ultrasound — the pus has nowhere to go and rupture is a matter of days.
• Signs of sepsis: temperature under 37.5°C, glucose over 250 mg/dL, lactate above 2.5 mmol/L, or a queen who will not eat.
• No improvement after 48 hours of correct antibiotics, or a relapse within 30 days.
• Uterine rupture or free fluid in the abdomen on the scan.
• The queen is not intended for another litter — then surgery also removes the risk of the next episode.

Surgery on a sick queen is not a routine spay. Expect $900–2,500 for an emergency ovariohysterectomy with fluids and 24-hour support, versus $250–600 for an elective procedure, and a 3–7 day recovery instead of 2.

Prevention sits in the breeding plan

Most metritis follows a difficult birth: keep the male's contacts clean and limited to one litter every 8–10 weeks, as described in stud cat management, and mate in the fertile window rather than on the first day she stands, per queen heat cycle timing. Weigh the queen daily for 5 days after delivery, count placentas against kittens, and call if the count is short.

For a queen you are finished breeding, spaying before her next heat removes the pyometra risk entirely. For one you are keeping, a 10-minute ultrasound 4–6 weeks after each heat is cheap insurance against finding a closed pyometra on the day she collapses.

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