Pyometra is an infection of the uterus in intact (un-spayed) female dogs and cats. This condition primarily affects middle aged to older female dogs and cats. Development of pyometra is hormone dependent and typically develops during the period of diestrus. Diestrus follows a heat cycle (estrus) and usually lasts for 60-90 days. During estrus, the cervix dilates in the female allowing for bacteria to ascend into the uterus. During the diestrus, progesterone is secreted. Progesterone causes the cervix to close as well as decreases immune function. The function of progesterone is very important in maintaining pregnancy, however in the non-pregnant bitch or queen it can lead to a life threatening uterine infection.


The majority of dogs and cats presenting with pyometra have a recent history of being in heat. The average time from estrus to development of pyometra is about 30 days but pyometra can develop at any time during the diestrus cycle. Pyometras are classified as open cervix or closed cervix. In an open cervix pyometra, vaginal discharge is typically observed. This discharge may be bloody, pus-like or mucoid. In a closed cervix pyometra, vaginal discharge is not seen.

Clinical signs of pyometra can include vaginal discharge, fever, increased thirst and urination, vomiting, decreased appetite, painful abdomen, elevated heart rate and pale or injected gums. Signs of shock can occur secondary to infection and toxins released from bacteria residing in the uterus.


Abdominal xrays are recommended for diagnosis of pyometra. A large tubular structure located between the urinary bladder and the colon is consistent with pyometra. Xrays can also show evidence of free fluid in the abdomen which could indicate that the uterus has ruptured. Ultrasound is another diagnostic tool that can be used to diagnose pyometra. Ultrasound is more sensitive than xray for differentiating between pyometra, pregnancy and cancer.


The recommended treatment for pyometra is a surgical ovariohysterectomy (spay procedure). Patients should be stabilized before surgery with IV fluids and antibiotics. Prognosis for dogs and cats following an ovariohysterectomy for a pyometra is excellent.

Whenever your pet is showing signs of a health issue your first step is to contact your primary care veterinarian. If it is indicated that your pet may suffer from pyometra or another serious condition, a veterinary specialist is available at an ExpertVet certified hospital.

Medical management of a pyometra can be considered only if the bitch or queen is a valuable breeding animal. Medical management of a pyometra is an option if the patient is mildly affected and the pyometra is open cervix. Under the supervision of a clinician experienced in reproduction, hormones can be given to cause contraction of the uterus leading to evacuation of infected fluid. These hormones also end the diestrus period. In addition, the patient must be managed in hospital with IV fluids and antibiotics. Side effects with this treatment are common and include vomiting, nausea, anxiety and abdominal pain. If medical management does not result in improvement then surgery should be performed immediately.