Pyometra Female Dogs

Pyometra Female Dogs, is a serious bacterial infection of the uterus that occurs most often in older, intact (unspayed) female dogs and cats. The most common bacterium identified in pyometra is E. coli, which typically originates in the feces and ascends through the vagina into the uterus. The infection tends to occur about a month after the dog or cat has been in heat. If unrecognized and untreated, pyometra can lead to a systemic infection or blood poisoning.

Pyometra is often described as being “open” or “closed.” With “open” pyometra, the cervix (the part of the uterus that connects with the vagina) is open, allowing the fluid that forms in the uterus due to the infection to drain out of the body through the vagina.

With “closed” pyometra, where the cervix is closed, the fluid in the uterus cannot drain through the vagina. Instead, it builds up, stretching the uterine walls and potentially causing the the uterus to rupture. If this occurs, the infection may spread throughout the abdomen leading to shock and, potentially, death.

X-ray showing pyometra in a dog

Risk Factors

The condition is most common in older, unspayed dogs that have never had a litter, but it can occur in any female dog or cat that has not been spayed. About 25% of unspayed dogs will develop pyometra before the age of 10.

Cats develop pyometra much less commonly than dogs. In a study from Sweden, Sphynx, Siberian, Ocicat, Korat, Siamese, Ragdoll, Maine coon, and Bengal cats had a greater risk developing pyometra than other cats.


Early in the course of pyometra, there may be no clinical signs. As the infection worsens, signs may include:

  • Lethargy
  • Lack of appetite
  • Vomiting
  • Diarrhea
  • Excessive thirst
  • Frequent urination
  • White or bloody vaginal discharge
  • Cats may show very minimal clinical signs


Pyometra is often suspected in any ill, unspayed female who has vaginal discharge and has recently been in heat and is showing the clinical signs listed above.  Your veterinarian will likely recommend bloodwork and an abdominal x-ray or ultrasound. If your pet has vaginal discharge, your veterinarian may examine the discharge under a microscope for signs of infection.


In most cases, emergency surgery to remove the pet’s uterus is necessary. Pets with pyometra are often dehydrated, feverish, and may have low blood sugar that must be corrected prior to surgery. In preparation for surgery, intravenous fluids, antibiotics, and glucose may be administered. If dogs and cats recover from surgery for pyometra, they are expected to live a normal lifespan.


The best way to prevent pyometra is to have your pet spayed. Spaying removes the hormonal stimulation that causes heat cycles, and the uterine changes that allow pyometra to occur.

By The Animal Medical Center