What Is It?

Pyometra is a bacterial infection of the female dog, which occurs in the period after heat. It therefore affects only unsterilized females.

During the heat, in fact, the hormone progesterone is produced which prepares the uterus for pregnancy regardless of whether or not there has been mating. This causes the thickening of the glands of the uterus which become fertile ground for the development of embryos, but unfortunately also for bacteria.

During the heat period the cervix opens to allow sperm to enter. This, however, facilitates the entry of bacteria which then remain “trapped” when the cervix closes at the end of the cycle.

There are two types of pyometra:

  • Open uterine service;
  • Service closed.


Depending on the type of pyometra the symptoms can be completely different. What happens, in fact, is that in open pyometra the pus accumulated in the uterus escapes outside with a visible and worrying vaginal discharge.

In closed pyometra the pus remains inside the uterus and when it accumulates too much it causes progressive dilation. In this case, in the absence of an obvious symptom such as vaginal discharge, the owner is not aware of anything, and cannot explain where the other frequent symptoms, such as:

  • lethargy;
  • felling;
  • inappetence;
  • dewatering;
  • excessive thirst;
  • frequent urination.

Predisposing Factors

Pyometra can affect any bitch of any race or age, as long as it is not sterilized. In some cases, certain factors contribute to the development of the disease:

  1. Ovarian cysts, which cause heat changes.
  2. Medication for terminating pregnancy.

Very often vets hear this request. Terminating pregnancy through the administration of sex hormones increases the chances of pyometra development disproportionately.

This is why many vets refuse to administer these drugs, knowing that they will have to resort to surgery to repair the damage done.


The most effective way (and the only one to be implemented) to treat pyometra is surgery to remove the uterus and ovaries. Recovery can take place relatively quickly if the dog was in good physical condition before the operation.

If the infection is already extensive, a long period of hospitalization will be necessary in the post-operative, with the administration of antibiotics, intravenous rehydration, periodic blood tests and all that is necessary for the dog to survive.

Without wanting to frighten anyone: pyometra, if left untreated, leads to the death of the dog. Are we still sure we don’t want to sterilize?