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Feline Pyometra - A breeders worst enemy


The word “pyometra” is derived from Latin “pyo” meaning pus and “metra” meaning uterus. Feline 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. 


What are the precursors to Pyometra?


Feline Pyometra can be caused from many different things, with E. Coli and Staph infections being the two main causes.


Classically, the patient is a younger female cat. Pyometra it’s not nearly as common as one might think. Usually, the cat has just finished a heat cycle in the previous 1-2 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.


There is also a form of feline 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. Other reasons are as follows:


It can be promoted from secondary systemic bacterial infection, post copulation, cystic endometrial hyperplasia, from estrogen to treat vaginitis, post partum metritis or it can sponteously occur.

Below are illustrations of both a normal and Pyometra filed uterus


A normal and pyometra filled uterus

Is there 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 “prostaglandin’s” are given as injections to cause the uterus to contract and expel its pus. The main prostaglandin’s used is called (Lutalyse®). 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.


PROS: 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 anesthetic risk


CONS: feline 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. With each heat cycle, the uterine lining engorges in preparation for pregnancy. Infection can be activated by hormonal changes during this time. Eventually, some tissue engorgement becomes excessive or persistent (a condition called “cystic endometrial hyperplasia”). This lush glandular tissue is ripe for infection (the inside of the uterus is sterile, the vagina below is normally loaded with bacteria.). During estrus the cervix opens and bacteria is allowed to get in. Bacteria ascend from the vagina and the uterus becomes infected, also getting trapped as the cervix closes and ultimately pus filled. The warm and wet environment is perfect for the growing of the bacteria. E-coli and streptococcus are part of the normal bacteria in the vagina and are a frequent cause of bacterial pyometra.

There are some important statistics that you should know about this form of treatment:


  • 1. The success rate for treating open-cervix Pyometra is 75-90%

  • 2. The success rate for treating closed-cervix Pyometra is 25-30%

  • 3. The rate of recurrence of the disease is 50-75%

  • 4. The chances of subsequent successful breeding are 50-75%


What is likely to happen if I do nothing?


The chance of successful treatment without surgery or prostaglandin treatment is extremely low. If treatment is not performed quickly, the toxic effects from the bacteria will be fatal. If the cervix is closed, it is also possible for the uterus to rupture, spilling the infection into the abdominal cavity. This will also be fatal.


Article by Gary Fulgham and may not be copied, reproduced or reprinted without written authorization


Disclaimer: Any medical advice given here is strictly the author’s opinion, and is not intended as advice. It is not intended to diagnose or offer treatment for an individual animal. A qualified Veterinarian should be consulted for any medical condition.