Case of the month: Crewman's Pyometra

Posted by on 15 January 2014

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Case of the month: Crewman’s Pyometra

 Reason for visit:

Crewman is a seven year old female Huntaway Cross. Her owners had noticed over the previous week that she had been limping on and off on both her front and back legs.  She was also lethargic and had been drinking and urinating more than usual.  Her appetite was reduced and on the day she came to see Colin she had not eaten at all.  Crewman was not spayed and had finished her season a couple of weeks earlier.

Examination findings:

Crewman had a temperature of 39.4 (mild fever).  Based on the history and finding of a fever, Colin was very suspicious that Crewman had a Pyometra and recommended an immediate abdominal ultrasound examination.  On ultrasound her uterus was found to be fluid filled confirming the suspected diagnosis of Closed Pyometra.

What is a Pyometra?

Pyometra is defined as an infection in the uterus.  It is a relatively common disease which occurs almost exclusively in unspayed female dogs.  Pyometra can occur suddenly and is considered a serious and life threatening condition that must be treated quickly and aggressively. Untreated it is often fatal.


Pyometra is a result of hormonal and structural changes in the uterus lining.  It can occur at any age, but is more common in females as they age. The main risk period is the two months following a heat.  Normally during this period, the cervix, which was open during heat, begins to close, and the inner lining begins to adapt back to normal. However, cystic hyperplasia of the endometrium (inner lining of the uterus) – known as cystic endometrial hyperplasia (CEH) – may occur at this time for some animals, as an inappropriate response to the hormone progesterone.

Under these circumstances, bacteria (especially E. coli) that have migrated from the vagina into the uterus find the environment favorable to growth. Whether the cervix is open or closed is a major factor in the severity of the condition.

  • If the cervix is open, the infected material can leave the body, and this is far easier and safer to treat. This is known as open pyometra.
  • If the cervix is fully closed, there is no discharge from the vulva, and like in appendicitis, the uterus may rupture and pus escapes into the abdomen, causing peritonitis and possible rapid death. This is known as closed pyometra.

Use of hormone injections to delay the onset of heat or cause abortion significantly increase the risk of Pyometra hence our reluctance to use these drugs.

The most obvious symptom of open pyometra is a discharge of pus from the vulva in a female that has recently been in heat. However, symptoms of closed pyometra are less obvious. Symptoms of both types include vomiting, loss of appetite, depression, increased drinking and urinating and shifting lameness.  Closed pyometra is a more serious condition than open pyometra not only because there is no outlet for the infection but also because a diagnosis of closed pyometra can easily be missed.  Diagnosis is confirmed by the finding of an enlarged uterus on x-ray or enlarged fluid filled uterus on ultrasound.

The preferred treatment is to surgically remove the infected uterus and ovaries (spaying / ovariohysterectomy)


After discussion with Crewman’s owners it was decided that she should undergo an emergency spay operation.  She was stabilized on intravenous fluids and antibiotics and then had surgery to remove the abnormal uterus and ovaries.  She was discharged later the same day on antibiotics, pain relief and strict rest.

Pyometra 3


Crewman was examined two days post surgery.  Her surgical wound was looking great and she had a normal temperature.  Her appetite was back to normal and she was back to her usual tricks at home.  The lameness and increased drinking and urinating had resolved. Crewman had a final examination ten days post surgery and was given a clean bill of health.

Take home message:

The good news is that pyometra is preventable. If your dog is successfully spayed before her first season, she will be best protected from this and many other reproductive diseases. It is also worth considering that a young, healthy dog is more likely to have an easy recovery than an older bitch following a spay operation.


Owners of breeding bitches can still protect their valuable pets by tracking their seasons and closely monitoring any changes in behavior.