Pyometra refers to infection of the uterus; therefore it cannot occur in speyed (desexed) bitches.
How does pyometra occur?
Bacteria from the vagina gain access to the uterus through the cervix that is open during oestrus (also known as "heat" or being "in season"). They colonise the lining of the uterus after oestrus when the lining is thickened due to the influence of hormones. Pyometra is most often seen around 8 weeks after heat in the non-pregnant bitch.
How is pyometra diagnosed?
Signs of pyometra include inappetance, depression, excessive thirst and vomiting. If these signs occur 8 to 10 weeks after oestrus then pyometra could be the possible cause.
Pyometra may be "open" or "closed", which refers to the state of the cervix. In open pyometra, pus can escape from the uterus, resulting in a vaginal discharge. No discharge is seen in closed pyometra, so an X-ray may be required to confirm the presence of an enlarged pus-filled uterus. Blood tests will indicate the presence of infection. Since kidney failure can occur in pyometra, your vet will perform blood and urine tests to check your dog's kidney function.
What is the treatment?
Pyometra is usually a surgical emergency, since it is fatal without treatment. If your dog is severely affected, she may need to be stabilised with intravenous fluids and antibiotics before surgery. Some dogs will die despite surgery due to overwhelming infection causing septic shock.
If the dog is a valuable breeding bitch and the pyometra is open, medical treatment may be effective, although the rate of recurrence is high and the dog may not respond, becoming critically ill in the meantime. Medical treatment with prostaglandins is therefore not recommended. Your vet will be able to advise you on your dog's specific prognosis and advise treatment.