by Dr Olivia Down
A pyometra is a bacterial infection in the uterus of a female dog. The condition occurs when there is bacterial invasion of the endometrium of the uterus. This usually occurs a few weeks after the dog has been ‘on heat’, but the time frame is variable relative to the heat cycle. When the uterus is exposed to high concentrations of hormones (estrogens and progesterone) without pregnancy, it can lead to a cystic lining of the uterus which provides an excellent environment for bacteria to colonise. The infection usually results from ascending bacteria through a partially open cervix during the ‘heat’ part of the dog’s cycle.
Pyometra most commonly occurs in females >6 years of age, however we have also seen the condition in younger dogs, and occasionally in very young female dogs. It is most commonly diagnosed 1-12 weeks following the dog being ‘on heat’. 1 in 4 undesexed female dogs will develop a pyometra during their lifespan.
Signs of a pyometra are generally that of a very unwell dog, such as lethargy, inappetance, vomiting, depression, and sometimes a visibly enlarged abdomen can be seen. A pyometra can be ‘open’ or ‘closed’. In an open pyometra the pus discharges out of the vagina – as seen by a yellow, green or red/brown copious discharge from the vulva of the dog. The diagnosis of an open pyometra is therefore easier if there is a visible discharge.
A closed pyometra is when the cervix is closed and there is no discharge. This can result in a severely distended uterus which is at risk of rupturing. Sometimes we use other diagnostic tests such as blood tests, ultrasound or x-ray to make the diagnosis of a pyometra.
In any case a pyometra is a serious life threatening condition in a female dog. It can rapidly lead to bacterial septicaemia and then death if left untreated. The treatment involves rapid intravenous fluid therapy and antibiotics, followed by surgery once the patient is stable for a general anaesthetic. The surgery required is an emergency ovario-hysterectomy (spey) to remove the uterus. Antibiotics alone are not successful in the treatment of a pyometra.
Pyometra is easily prevented by desexing your female dog, which we recommend doing at 4-6months of age.