This is a serious bacterial infection of the uterus. The word literally means pus in the uterus. It is a condition of un-spayed female dogs and very occasionally cats.
It happens after several successive heat cycles without being bred and having a litter. There are changes that develop within the uterus which can support the growth of substantial amounts of bacteria. It can occur in any breed and at any age but is most prevalent in middle age.
The symptoms may be quite vague and can mimic many other conditions. They will usually develop 1-2 months after a heat cycle. Signs might be as subtle as decreased appetite and a little more lethargic than usual, or they may be much more obvious, such as vomiting and depression. Some animals have a dramatic increase in thirst and urination. There can be a vaginal discharge that may be blood or pus or a mixture of these.
Untreated, this can be a life threatening condition from either septicemia (blood poisoning) or the uterus rupturing leading to peritonitis (infection of the abdominal cavity).
Treatment for this condition is an emergency spay along with supportive care such as intravenous fluids and antibiotics as well as post-surgical antibiotics, pain killers etc.
Prognosis is good with prompt treatment.