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.

Classically, the patient is an older female dog. (Pyometra can occur in cats but it is not nearly as common.) Usually, she has finished a heat cycle in the previous 1 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 are able to drip out, thus a smelly vaginal discharge is usually apparent.

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.

How does this Infection Come About? 

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.

What is the Usual Treatment? 

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 hemorrhage 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 this 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. For these reasons, the pyometra spay typically costs five to ten times as much as a routine spay.

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

Prevention 

Spaying represents complete prevention for this condition. Spaying cannot be over-emphasized. Often owners plan to breed their pet or are undecided, time passes, and then they fear she is too old to be spayed. A female dog or cat can benefit from spaying at any age. The best approach is to figure that pyometra will eventually occur if a female pet is left unspayed; any perceived risks of surgery are very much out-weighed by the risk of pyometra.