Pyometra is a serious infection of the womb resulting in the accumulation of infective fluid (pus) within the cavity of this organ. It is usually seen in older, female cats and dogs who have not been neutered.

Pyometra may be classified as open or closed. In open pyometra, a common sign is a discharge from the vagina. This discharge may be bloody or yellow or cream coloured. In closed pyometra, no discharge to the exterior occurs. If the pus does not drain out though the vagina, your dog may become very sick and
develop toxaemia (blood poisoning).

The presence of this poison in the body has serious effects on otherbody organs and systems and can lead to life-threatening conditions such as kidney failure.

Untreated pyometra, can cause death from dehydration, toxaemia and kidney failure.

A less common problem, stump pyometra, occurs in females who have been spayed (neutered), but in which a small remnant of womb remains within the body and becomes infected. Because only a small amount of womb is present, signs tend to be less severe, but this condition also needs treated to prevent complications.

What causes pyometra?

Each time a female has a season (usually about twice a year) she undergoes all the hormonal changes associated with pregnancy - whether she is pregnant or not. The changes in the womb that occur with each cycle make infection more likely with age. Infection is usually caused by a very common organism
called E. coli. The disease often occurs in the weeks or months following a heat or season period. Injections with some hormones to stop seasons or for treatment of other conditions can also increase the risk of pyometra developing.

What are the signs of pyometra?

Pyometra is obviously only seen in females (since males do not have a womb). It is more common in older females (above 6 years of age). The signs usually develop around 6 weeks after the female has finished bleeding from her last season. Early signs of pyometra may not be very obvious. You might notice that your pet is just licking her back end more than usual. She may be off colour and off her food. Often she will be very thirsty and because she is drinking so much may start to wet in the house. Sometimes the puss escapes from the womb and a reddish-brown or yellow discharge may be seen at the vulva. As she gets more ill she may start to vomit, become very depressed and unwilling to get out of her bed. Symptoms are likely to worsen over a period of days to several weeks. If untreated signs progress to dehydration, collapse and death from toxic shock.

How do vets diagnose pyometra?

Your vet will probably suspect what is wrong with your pet from your description of the symptoms although they may want to do some other tests to confirm the diagnosis and also to make sure that your pet is well enough to withstand an operation. Blood tests may be taken to see if the toxins from the infection have entered the blood and could be affecting organs elsewhere. X-ray and ultrasound examinations may be undertaken to confirm that the uterus is enlarged.

Is there any treatment for pyometra?

Once the diagnosis has been confirmed your pet should have an operation to remove her womb as soon as possible. This is the same operation as carried out to routinely spay a female dog, however in a sick animal suffering from pyometra it carries much more risk. The risk of not operating is even higher; most animals will die if surgery is not performed. If the womb is not removed, toxins are released from the infection which get into her blood and make her more and more ill, Eventually these toxins can cause kidney failure.

Before performing the operation your vet may want to give your pet some fluids (into her vein) and antibiotic treatment. Surgery might be delayed for 12-24 hours to give your vet time to get your pet into a better condition to tolerate the surgery. She may need to stay in hospital after surgery for continued treatment.
Very occasionally dogs have been treated with special hormone injections to empty the womb without having to perform an operation. However, this treatment is only considered in valuable breeding bitches and is often not successful. In very old animals with pyometra and clear evidence of organ failure, eg kidney and liver failure, or where other major problems such as serious heart disease exist, euthanasia may be the kindest option.

Will my dog get better?

Pyometra is a serious disease and unfortunately a proportion of patients will not pull through despite treatment, owing to organ failure and complications. Overall, many dogs and cats do recover remarkably well and it is certainly well worth pursuing treatment.

If your pet recovers from the operation then there is a good chance she will return to her former health. In fact many owners report that after the operation their dog or cat is better than she had been for a long time before. It may be that the infection had been building up for a long time before the animal became really ill.

How can I stop my dog getting pyometra?

The only way to be sure your pet won't develop this condition is to have her neutered. If you are not intending to have puppies from her then she should be neutered at as young an age as possible. Not only does this remove all the complications associated with the reproductive cycle but, if a female is neutered before her first season, she is also protected against mammary (breast) cancer developing in later life. Ask your vet for details about the best time to have your pet neutered. 

Although pyometra may be more common in bitches that are not neutered and have never had puppies, it is not exclusively a disease of these animals. Breeding does not guarantee protection and indiscriminate breeding of pet dogs and cats is not to be encouraged.