Pyometra is a condition affecting unspayed bitches (and less commonly cats) where the womb, or uterus, becomes infected. In mild cases it can come on fairly slowly with only slight changes in the uterus, but the worst cases happen very quickly and the womb becomes swollen like a balloon, but filled with pus. These are urgent and life-threatening.
Pyometra happens when the lining of the uterus (the endometrium) changes under the influence of the bitch’s hormonal cycle. It nearly always happens a few weeks after she has been in season and is more common in older bitches. The use of certain hormonal drugs to postpone seasons has been linked with an increased risk of pyometra. Rarely, a spayed bitch can develop a similar infection in the remaining part of the uterus, called a “stump pyometra”, but this is uncommon.
The first symptoms are not very specific, with the bitch appearing a little unwell and off her food. Usually the thirst will increase and there may be some vomiting, but not all symptoms happen in all cases. If the cervix (the junction between the uterus and the vagina) remains open, there is often an unpleasant vaginal discharge. If the cervix is closed, the discharge cannot escape and these cases are more serious. The temperature may be raised, and when toxins enter the bloodstream the bitch will become seriously ill. In a small number of cases, kidney failure and death will result.
It is usually easy to diagnose a pyometra from a combination of the history and the physical examination. If there is any doubt, x-rays or ultrasound scans can help in the diagnosis. Blood tests can also help by confirming high levels of infection-fighting white blood cells.
The treatment for pyometra is the surgical removal of the uterus and ovaries, also called ovaro-hysterectomy or spay. It is a more difficult operation in a bitch with pyometra than the regular spay operation in a young healthy bitch. The uterus is often enlarged and fragile. If it should leak or burst, there is a high risk of peritonitis. Having said that, the operation is nearly always successful. It is usually carried out immediately after diagnosis, unless the bitch needs to be stabilised first to allow her a better chance of coming through the operation.
After-care would include antibiotics and possibly fluids by drip if the bitch was very poorly. Exercise will be restricted for a minimum of 10 days while the wound heals, and pain relief will be given.
There have been attempts to treat pyometra with drugs rather than surgery, but it is unlikely that severe cases would respond to anything but surgery. In mild cases which improve for a time there is every chance that the condition will come back after the next season.
It is often said by owners after the bitch has recovered from a pyometra operation that they are healthier than they have been for years. In these cases the condition had probably been grumbling for a long time but not enough to worry anyone until recently. The changes in the bitch’s behaviour which had been put down to advancing years are reversed, often giving a whole new lease of life.
The best way to prevent pyometra is to spay whilst the bitch is young and healthy. Unless you really want puppies, with all the responsibility and expense that goes with them, it is best to spay either before the first season or about three months after it. Your own vet can advise on the best time for your particular bitch. The added advantages of spaying young are the reduced risk of mammary tumours and the avoidance of further seasons and unwanted pregnancies. There could be a slightly increased risk after spay of developing urinary incontinence, and some bitches develop a fluffy coat instead of a sleek shiny one. These drawbacks are greatly outweighed by the benefits.
It is always a good idea to take note of changes in your dog’s behaviour or general wellbeing. Noticing small changes in appetite or thirst could be crucial in diagnosing this type of condition early. If you are worried about any of these symptoms, always ring your veterinary surgery for advice.
Our Interactive Symptom Guide can help you check out any unusual symptoms and advise on how soon you should visit your vet. Earlier diagnosis usually means more successsful treatment.