Pyometra describes a pus filled, infected uterus. It is a life threatening condition that requires emergency stabilization and surgery for treatment. Intact (non-spayed) female dogs are at risk for developing pyometra.

Pyometra usually occurs after a heat cycle in which the dog did not become pregnant. Typically, pyometra most often develops around eight weeks following the heat cycle. It should not be confused with metritis, which is a uterine infection that develops following the birth of puppies.

Pyometra can be defined as open (draining pus out of the vagina through an open cervix) or closed (pus is trapped in the uterus due to a closed cervix). Closed pyometras are more dangerous, since the infection is trapped in the dog's body.

The infection is not only life threatening on its own, but it can also cause kidney failure through bacterial toxins. If treated quickly with surgery and antibiotics, approximately 90 percent of dogs affected with pyometra will survive.