If you own an intact female herding dog, this is the one condition I most want you to understand before it happens. Pyometra — an infection of the uterus that fills the womb with pus — is common, it is deadly, and it moves fast. I have seen healthy six-year-old bitches go from “a bit off her food” to collapsed and septic in under 72 hours. The owners almost always say the same thing afterwards: “I didn’t know it was urgent.”
So let me make it plain. Any unspayed bitch who is drinking more than usual, off her food, or producing a discharge in the weeks after a season needs to be seen the same day. Not next week. That day.
Why It Happens, and When
After every heat cycle, a bitch’s body floods the uterus with progesterone to prepare for a possible pregnancy. Progesterone thickens the uterine lining and dampens the local immune response. That combination — a thick, glandular lining with reduced defences — is the perfect environment for bacteria, usually E. coli from the dog’s own gut, to take hold.
This is why pyometra typically strikes four to eight weeks after a season, not during it. Each cycle a bitch goes through without becoming pregnant adds a little more change to the uterine lining (a process called cystic endometrial hyperplasia), which is why the risk climbs steadily with age. The classic patient is a middle-aged to older intact bitch — six, eight, ten years old — who has had a number of seasons and never been bred.
It is worth knowing that pyometra is not a disease of neglected dogs. It happens to pampered, well-cared-for, perfectly healthy bitches. Being intact is the only real risk factor that matters.
Open Versus Closed: The Distinction That Decides Everything
There are two forms, and they behave very differently.
Open pyometra means the cervix is open and the infected uterus can drain. You will see a discharge — often thick, bloody, yellow-green, and foul-smelling — from the vulva. Owners frequently notice stains on the dog’s bedding or a smell before they see anything else. Counterintuitively, this is the better version to have, because the pus has somewhere to go and the dog is less likely to be acutely septic when you reach the vet.
Closed pyometra is the dangerous one. The cervix is shut, so the pus has no escape. The uterus swells with infected fluid, sometimes to litres in a large shepherd, and the toxins are absorbed straight into the bloodstream. There is no discharge to warn you. These dogs deteriorate quickly into sepsis, and because there is no obvious sign pointing at the uterus, the cause is easy to miss until the dog is critically ill.
This is exactly why I tell owners not to wait for a discharge. The absence of one is not reassuring — it can mean the more lethal form.
The Signs Owners Actually Miss
The early picture is frustratingly vague, which is the whole problem. Watch for:
- Increased thirst and urination. This is often the very first change and the most overlooked. The bacterial toxins interfere with the kidneys’ ability to concentrate urine, so the dog drinks noticeably more. If your intact bitch is suddenly emptying the water bowl, take it seriously.
- Lethargy and dullness. She is flatter than normal, less keen to work or play, sleeping more.
- Reduced or absent appetite. Often comes a day or two after the increased drinking.
- Vomiting. A sign that toxins are circulating and the dog is becoming systemically unwell.
- Vulvar discharge in the open form — but, again, do not rely on this.
- A distended, tender abdomen in advanced cases.
Herding breeds make this harder, not easier. A Border Collie or working German Shepherd is bred to push through feeling unwell, so a stoic bitch will often mask the early stage. This is the same trap I describe in the wider problem of working dogs hiding pain and illness until it is severe — by the time the behaviour is obvious, the disease is well advanced.
Why Emergency Spay Is Almost Always the Answer
When I diagnose pyometra — usually with a quick combination of history, an ultrasound or X-ray showing a fluid-filled uterus, and bloods showing a raging infection — the treatment of choice is surgery to remove the infected uterus and ovaries (an ovariohysterectomy, the same operation as a routine spay but on a sick, friable, pus-filled organ).
It is not the same as a routine spay. The tissue is fragile, the uterus can be enormous, and the dog is often unstable under anaesthetic. We stabilise first with intravenous fluids and antibiotics, then operate as soon as she is fit enough — which is usually within hours, because every hour of delay risks the uterus rupturing and spilling infection into the abdomen. That complication, septic peritonitis, is frequently fatal.
People sometimes ask about medical management — drugs (prostaglandins) to make the uterus contract and expel the pus without surgery. It exists, but I reserve it for the rare, specific case: a young, valuable breeding bitch with the open form, stable and not yet septic, where the owner accepts a real risk of failure and recurrence. For the typical pet bitch, especially the closed cases, medical management gambles with her life to save a uterus she does not need. Surgery cures the condition outright.
The good news is that a bitch caught early and operated on promptly has an excellent prognosis. The dogs we lose are almost always the ones brought in late, already septic, with a ruptured uterus. The deciding factor is how fast the owner acts.
What This Means for the Spay Decision
Pyometra is the single strongest argument against leaving a bitch intact for life if you have no intention of breeding her. There is genuine, evidence-based debate about the best age to neuter a large herding breed — joint development, certain cancers, and behaviour all factor in, which is why I never tell owners to rush a young dog to surgery. But a bitch who is never going to be bred and is kept entire into middle age is carrying a real, cumulative risk that climbs with every season.
If you are weighing that decision, do it deliberately rather than by default. Have the conversation with your vet about timing, breed, and your individual dog, the same way you would plan any major health decision at one of her annual wellness exams. And keep this in mind: pyometra is not a maybe-someday risk for an intact bitch. It is a when, often enough that every owner of an entire female should know the signs by heart — and treat them, like any true emergency, as a same-day trip to the vet.