Pyometra is a very serious condion in dogs where the uterus fills with pus.  Just as in appendicitis, the uterus can burst and kill the dog.  This is another good reason to get a dog spayed — no uterus, no pyometra.

Pyometra normally occurs in middle aged or older intact bitches.  There are two kinds of pyometra, open and closed.  In the open version, the cervix remains open and the pus drains out through it.  In the closed version, the cervix closes and the pus is trapped in the uterus.  This is the most dangerous kind of pyometra because if the uterus ruptures from the pressure of the pus, the dog will be at risk of peritonitis, or abdominal infection.

Hormonal and structural changes in the lining of the uterus are the two main causes of pyometra.  The lining of the uterus thickens over many heat cycles and sometimes this thickening can persist.  It then provides a rich environment for bacteria to grow.  Normally, the uterus is free of bacteria.  When the bitch comes in heat, the cervix opens up and bacteria can enter the uterus.  Once there, the bacteria thrives and the uterus fills with pus.  E. coli is the main culprit in this infection, as it is in so many things.  Day after estrogen injection give to prevent pregnancy in bitches that have been accidentally bread have been shown to increase the chances of getting pyometra and should be avoided.

The best prevention for pyometra is to spay your bitch at an early age.  Spaying removes the uterus and ovaries and prevents them from ever getting infected.

Clinical signs of pyometra can vary but are very much like any abdominal problem.  They include not eating, vomiting, lethargy, increased water intake and increased urination.  In open pyometra, pus that is white or green may be discharged from the vulva.  There may also be a foul odor emitted from the vulva.  In closed pyometra, the abdomen looks bloated due to the uterus filling with pus.  Unfortunately, clinical signs for either type of pyometra are not normally seen until things are fairly well along.  The dog can get very sick very fast and can go into shock or die due to toxins from the uterus leaking into the abdomen.

Because the symptoms of pyometra can be so general, diagnosing it can be difficult.  Usually, the veterinarian will perform an ultrasound on the dog and rule out pregnancy or other causes for the enlarged uterus.  A culture may be run to determine what type of bacteria is causing the infection, so the veterinarian knows how best to fight it.

The preferred treatment for pyometra is to spay the dog.  This removes the problem organs and makes sure the problem does not reoccur.  In addition, the dog is given antibiotics and fluids to help her fight the infection.

If the dog is a valuable breeding dog, hormones may be given in addition to the antibiotics and fluids.  In open pyometra, this has a good chance of solving the problem.  In closed pyometra, the prognosis is more guarded.  In both kinds of pyometra, the problem will likely reoccur.  The bitch should be breed on the next heat and allowed to whelp her puppies, then be spayed.