Pyometra is an infection within the uterus that occurs in the unspayed female dog or cat. Bacteria gain access to the uterus usually from a urinary tract infection or from fecal contamination. Pus is able to accumulate due the influence of the hormones progesterone and estrogen which are released during the pet’s cycle.

The clinical signs occur approximately 4 to 6 weeks after a heat cycle. Pyometra can either be “closed” ­ meaning the cervix is closed and there is no outward drainage or “open” ­ meaning the cervix is open and there is visible drainage from the vulva.

Typical signs include lethargy, depression, poor appetite, vomiting, fever, increased thirst, abdominal distension or vulvar discharge (yellow or bloody). Some pets may only have discharge.

Diagnosis is confirmed by ruling out other abnormalities with bloodwork, radiographs, and ultrasound (if necessary). Bloodwork is important to assess the level of systemic infection and to determine if damage has been done to the kidneys by the infection (common problem). Diagnosis is usually confirmed with radiographs, which show a large fluid filled structure in the back half of the abdominal cavity.


The treatment of choice is ovariohysterectomy (spay). This is a medical emergency and requires immediate action as soon as the patient has been stabilized with IV fluids. Surgery removes the pus filled structure (uterus) and also the source of the hormones (ovaries). In effect, the current disease is resolved and future episodes are prevented.
Although medical therapy with hormones has been reported, it can not be recommended as the recurrence rate of pyometra is extremely high. This treatment is usually reserved for animals used for breeding purposes only (not pets) and one breeding may be all that is achieved.

Postoperative care consists of IV fluids to reverse kidney damage (when possible), antibiotics, pain medication, and nursing care. The success rate for pets with no renal compromise ranges from 85­100%.

Prevention consists of spaying your pet at the recommended age. This also decreases their risk of developing mammary cancer.