As a general practitioner, some of the most frequent procedures that are done in the clinic include the ovariohysterectomy (removal of the ovaries and uterus) of the female, and castration (removal of the testicles) of the male. During my time at Hird and Partner’s, I was lucky to have performed a few of these procedures under direct supervision. It was a great way to get obtain more surgical experience before having to perform them on my own in just one short year (is it really that soon?!).

While most clients chose to spay and neuter their pets at a fairly young age, there are patients that require these surgical procedures when they are older for various reasons. One of the important and life threatening conditions that require immediate intervention in an unspayed female is called a pyometra (pyo), or infection of the uterus. During my externship I was allowed to assist with an emergency ovariohysterectomy as the recommended treatment option for this condition.

So, what is this pyo that I speak of. Pyometra is a secondary infection that occurs as a result of hormonal changes within the reproductive tract. When a female dog enters her heat cycle (estrus), the immune cells that normally protect the tissue are inhibited to allow for the entry of sperm. After her heat cycle has completed, a hormone called progesterone remains elevated and thickens the lining of the uterus in preparation for pregnancy. Repeated estrus cycles with no pregnancy cause the uterus lining to continue to thicken, allowing bacteria to develop and impeding the ability of the uterus to contract and expel build up of bacteria and other material and allowing a perfect foundation for an infection to develop. The optimal time for this to occur is between four to eight weeks after a dog has been in heat.

A pyometra can take two forms. An open pyometra is one in which the cervix remains open and allows the pus to drain out, while a closed pyometra allows no drainage and the pus accumulates and distends the uterus. In an open pyo, the dogs do not always present quite as sick due to the constant drainage of bacteria. You may notice a foul smelling odour, and the dog may be a little quieter and depressed than usual. Closed pyo dogs appear much sicker and are at greater risk for a uterine rupture if not promptly treated.

Any unspayed female that presents with abdominal pain, abnormal vaginal discharge and an overall decrease in attitude will go through the steps to immediately rule out a pyometra. Bloodwork is often collected and an xray or ultrasound is taken which can identify a large, fluid filled uterus. Once detected, the preferred treatment is to surgically remove the infected uterus and ovaries after stabilizing the patient. Hospitalization with intravenous fluids and antibiotics are required. On a case-by-case basis, medical management may be attempted but does not come without significant risk and a high likelihood of recurrence of a pyometra.

I am pleased to say that with an emergency spay, the patient we saw did well and was a happy dog upon recovery. Her uterus weighed an incredible 6.5 kilograms (about 14 pounds)! The best way to avoid a pyometra is to spay dogs and cats prior to their first heat. Doing this will also significantly reduce the likelihood of other diseases including mammary carcinomas.