Pyometra: Womb 101

It’s one of the most well known serious life-threatening conditions for any bitch to endure, and frustratingly, one of the most easily preventable.

‘Pyometra’ literally denotes pus in the womb and is seen a lot less commonly these days due to increased awareness about neutering but is still found in any vet’s consulting room the length and breadth of the UK all year round.

Pyometra, or ‘pyo’ for short, can present from the obvious thick brownish pus seeping from the bitch’s vulva to the much vaguer signs of being a bit quiet and perhaps just off her food.

The reason for this wide spectrum of clinical signs boils down to both how long the pyo’s been established and whether the creamy festering pus is being allowed to drain out from the womb or not.

(Above) Typical pyometra sign of abnormal discharge from bitch’s vulva.

For example, a classic scenario would be an unspayed bitch with a noticeably increased thirst (polydipsia) who seems to be spending most of her time licking an abnormal (usually smelly) discharge from her private parts (above).

Perhaps her abdomen is also swollen and painful to touch and maybe she’s been acting tired, depressed, and even turning her nose up at food – even her favourite treats.

Occasionally they’ll exhibit a fever, have greyish gums (depending how advanced the pyo is) and will have been in season between one and three months ago, with some cases even having vomiting and diarrhoea too.

The above describes the classic ‘open’ pyo where open denotes that the bitch’s cervix is open, allowing the pus being produced in the uterus to freely flow to the outside and thus be visible on examination.

It’s no surprise then that the less obvious, or ‘closed’ pyo, occurs when the cervix remains tightly closed, providing an effective seal capable of withholding the pus and making the condition slightly less obvious to diagnose.

In any case the bitch’s symptoms coupled with a thorough investigation that may include blood tests, ultrasound, X-rays or even the decisive exploratory laparotomy will point to a positive diagnosis that can then be treated safely and efficiently.

But how does pyometra happen? Why all of a sudden does the bitch’s uterus decide to produce and subsequently fill up with horrible thick pus? Well the answer isn’t a simple one as pyometra can be caused by one or a combination of underlying factors.

These include the tiny microscopic behaviour of the womb lining itself, likely hormonal imbalances, as well as a source of infection – usually ‘ascending’ meaning entering the reproductive tract at the vulva from the outside world and creeping up, or perhaps via the blood stream from another infected area of the body.

If instead of having her last season the bitch has in fact recently given birth to a litter, an inflamed womb with bruised or exhausted and vulnerable tissues can also act as a focus for infection to set in.

Treatment options may vary depending on your vet but most will advise surgical removal of the infected uterus when it’s safe to do so.

Many patients with severe pyometra showing signs of being toxic or even in shock, will benefit from intravenous fluids, antibiotics and pain relief first to best prepare for the surgery, general anaesthetic and its potential knock-on effects on the patient.

More recently, a short course of the same injection we use for cases of misalliance (mis-mating) has been shown to effectively expel pus from an infected uterus and normalise the bitch even further making them an even safer candidate for successful treatment.

But if pyometra is just an infection why can’t we just treat with antibiotics you may ask?

Well due to the thickness and amount of pus, any antibiotics injected or ingested orally are delivered to the diseased tissues via the bloodstream and rarely penetrate the infection effectively, and even if they did the bitch’s underlying medical conditions e.g. abnormal hormone levels, would normally mean a recurrence post-treatment.

So to cure a bitch with pyometra, surgical removal of the infected uterus is usually almost always indicated and we’ll also remove the bitch’s ovaries at the same time, i.e. a bitch spay.

(Above) Pictures taken during a pyometra spay of a bitch called Holly (left) and normal routine spay (right) indicating obvious change in uterine appearance (Pic from

The main differences operation-wise between pyometra spay and a normal routine spay (above) can be increased risk of abdominal contamination to the patient (due to infected tissues that may be fragile and break down when touched), and cost as many pyometras will present at night in emergency hours requiring full clinical investigation including perhaps a couple of days hospitalisation on fluids.

Pyometra is certainly one of the biggest reasons us vets advise you to get your bitch spayed if they’re not being bred from. Other benefits include drastically decreasing the risk of developing mammary (breast) cancer as well as preventing any inconvenience of your bitch coming into heat every few months (e.g. cream-coloured carpets, unwanted attention from male dogs, etc).

Spaying a bitch with pyometra is usually 100% successful and the patient usually makes a full and uneventful recovery with a good prognosis.

So the moral of this story is, if you own an unspayed bitch and you don’t plan to breed from her, please ask your vet about spaying, as an emergency pyo operation in the middle of the night is the last thing she or you need when it can all be taken care of as a much safer routine procedure in daylight hours with a lot less risk to the patient.

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