Recently, a 10-year-old female Golden Retriever presented to the hospital for lethargy, decreased appetite, and vaginal discharge. Since she had not been spayed, infection in the uterus, otherwise known as pyometra (pyo is Latin for pus and metra means uterus), was immediately suspected.

This is a problem in older unspayed female dogs and less commonly in unspayed female cats. The clinical signs typically occur about 1-2 months after the last heat cycle. During each heat, the lining of the uterus becomes engorged in preparation for pregnancy. In time, this tissue becomes excessive and persists beyond the usual heat cycle, causing cysts to form in the uterine lining. The tissue is very susceptible to infection, and if bacteria are able to travel up from the vagina into the uterus, an infection develops resulting in a uterus filled with pus.

The classic patient is lethargic with a poor appetite and may be drinking excessive amounts of water as well as vomiting. She may have a fever, painful abdomen, and can even be in shock. The sicker patients that we see have a ‘closed’ pyometra, meaning the cervix is not dilated and there is no vaginal discharge. This makes diagnosing the problem a bit more challenging. Closed pyometra is a life-threatening problem and these animals are more ill because the toxins from the bacteria are trapped in the uterus and then travel into the bloodstream. If the pyometra is ‘open,’ this means the cervix is dilated allowing pus to leak out of the uterus which we see as a foul-smelling vaginal discharge. This helps to diagnose the problem but does not change the recommended treatment.

Blood work, x-rays, and ultrasound aid in the diagnosis. Often the white cell count is high because the body is fighting a large infection, and the kidneys can be damaged by the bacterial toxins resulting in increased renal enzymes. A large, dilated uterus can sometimes be seen on x-rays of the abdomen, especially in closed pyometras. But abdominal ultrasound, if available, is the more sensitive test for identifying an enlarged uterus.

Once diagnosed, the recommended treatment for either a closed or open pyometra is the same – surgical removal of the uterus and ovaries. These patients need be stabilized as much as possible first with IV fluids and are usually started on IV antibiotics, but should go to surgery as soon as possible. Delaying surgery puts the patient at risk for rupture of the uterus and septic shock.

While the end result of a pyometra surgery and routine spay are the same – removal of the uterus and ovaries – the patient with the pyometra  is at a much higher risk for serious complications such as bleeding, peritonitis, septic shock, and chronic renal failure. For these reasons, the cost of pyometra surgery and post-operative care can be 5 to 10 times higher than a routine spay.

The risk of an unspayed dog developing pyometra before the age of 10 is 23-25%. Prevention of pyometra is simple – spay any female pets that are not going to be used for breeding or are retired from breeding. It is important to know that there are very few diseases or problems that would preclude anesthesia and surgery, even in our older pets. The benefit of routine spaying far outweighs the risk of undergoing surgery with an infected uterus.

As for our 10-year-old Golden Retriever with the open pyometra, after a few hours on IV fluids, she was taken to surgery. She did very well during and after surgery, and was discharged from the hospital after 2 days to the care of her owners.

Roz Elliott, DVM