WHAT IS A PYOMETRA

The word “pyometra” is derived from latin “pyo” meaning pus and “metra” meaning uterus. The pyometra is an abscessed, pus-filled infected uterus. Toxins and bacteria leak across the uterine walls and into the bloodstream causing life-threatening toxic effects. Without treatment death is inevitable.

Pyometra is a lethal infection that occurs when bacteria build up within the uterus. Classically, the patient is an older female dog. Usually, she has finished a heat cycle in the previous l to 2 months. She has a poor appetite and may be vomiting or drinking an excessive amount of water. In the more usual “open pyometra” the cervix is open and the purulent uterine contents is able to drip out thus a smelly vaginal discharge is usually apparent; however, there is also a form of pyometra called a “closed pyometra” where the cervix is closed. In these cases, there is no vaginal discharge and the clinical presentation is more difficult to diagnose. These patients also tend to be sicker than those with open pyometra due to retention of the toxic uterine contents.

Lab work shows a pattern typical of widespread infection which is often helpful in narrowing down the diagnosis. Radiographs may show a gigantic distended uterus though sometimes this is not obvious and ultrasound is needed to confirm the diagnosis.

With each heat cycle, the uterine lining engorges in preparation for pregnancy. Eventually, some tissue engorgement becomes excessive or persistent (a condition called “cystic endometrial hyperplasia”). This lush glandular tissue is ripe for infection (recall that while the inside of the uterus is sterile, the vagina below is normally loaded with bacteria.). Bacteria ascend from the vagina and the uterus becomes infected and ultimately pus filled.

The usual treatment for pyometra is surgical removal of the uterus and ovaries. It is crucial that the infected uterine contents do not spill and that no excess haemorrhage occurs. The surgery is challenging especially if the patient is toxic. Antibiotics are given at the time of surgery and may or may not be continued after the uterus is removed. Pain relievers are often needed post-operatively. A few days of hospitalization are typically needed after the surgery is performed.

It is especially important that the ovaries be removed to remove future hormonal influence from any small stumps of uterus that might be left behind. If any ovary is left, the patient will continue to experience heat cycles and be vulnerable to recurrence.

While pyometra surgery amounts to the same end result as routine spaying, there is nothing routine about a pyometra spay. As noted, the surgery is challenging and the patient is in a life-threatening situation.

The infected uterus is normally resolved rapidly (in an hour or two of surgery). No possibility of disease recurrence but surgery must be performed on a patient that could be unstable.

 AN ALTERNATIVE TO SURGERY

In the late 1980’s another treatment protocol became available that might be able to spare a valuable animal’s reproductive capacity. Here, special hormones called “prostaglandins” are given as injections to cause the uterus to contract and expel its pus. A week or so of hospitalization is necessary and some cramping discomfort is often experienced. The treatment takes place over the course of a week. This form of treatment is not an option in the event of a “closed” pyometra as described above.

There is a possibility of future pregnancy for the patient (though often there is too much uterine scarring). Surgery can be avoided in a patient with concurrent problems that pose extra anaesthetic risk.

Pyometra can recur. The disease is resolved more slowly (over a week or so). There is a possibility of uterine rupture with the contractions. This would cause peritonitis and escalates the life-threatening nature of the disease.

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