At Molecare, we recommend that any bitch not intended for breeding is spayed. One of the main reasons for this is the risk of pyometra.

Pyometra is a life-threatening infection of the uterus (womb) and must be treated quickly and aggressively. The infection is direct result of hormone fluctuations after a bitch’s season/heat.

Three main factors contribute to the development of pyometra:

  1. During your bitch’s season, white blood cells from the immune system are reduced in the reproductive tract to permit safe passage for sperm to allow fertilisation. These white blood cells would normally protect against infection, so the womb is at risk of infection when these are low. The bacteria involved are often those normally found in the vagina in small numbers that move through the cervix when it is more relaxed during oestrus (‘heat’).
  2. The reduced white blood cells generally don’t cause problems while bitches are young, however with each season that passes, the lining of the womb will become thicker and can be prone to developing cysts. The thickened, potentially cystic lining of the womb will release fluids that provide the perfect environment for bacteria to thrive, and numbers can increase.
  3. Add to this that high levels of a hormone called progesterone reduce movement in the muscle wall of the womb, meaning that the uterus cannot contract to expel accumulated fluid or bacteria.
  4. Pyometra generally starts to affect the bitch between 2 and 8 weeks after the end of the season/heat.

 Which dogs are affected?

The combination of the above changes mean it is easier for bacteria to take hold as a bitch becomes older. Older bitches are much higher at risk of developing the infection, and they are in a poorer position to cope with the impacts on the body. Spaying a bitch almost eradicates the risk of infection as the womb is usually completely removed during surgery.


The severity of symptoms will depend on whether the cervix is open or tight shut, but it is likely that the bitch will be drinking more regardless. If the cervix is open, smelly discharge may be seen around the vulva. She may be lethargic, off her food and feverish. If the cervix is closed, the pus is not able to drain from the womb and as it accumulates, the womb stretches to bursting point. The bacteria release toxins into the blood and these dogs may become seriously ill very quickly. They are often off food, listless and depressed and may have vomiting or diarrhoea.


Our diagnosis will be based on the history you give us as well as our clinical examination. If we are concerned about pyometra we will recommend an ultrasound to check the womb and a blood test.


Generally, we recommend surgical treatment to remove the womb and ovaries and therefore remove the infection. This is emergency surgery and if deemed necessary, must not be delayed. If the cervix is open, it is sometimes possible to control the pyometra medically with hormone therapy. Antibiotics alone will not resolve the infection as it is being driven by hormones and the hormones themselves need to be targeted. Without treatment the condition is often fatal.

If surgery goes well, most dogs will go on to make a full recovery. Relapses are more common if medical hormone treatments are opted for.

If you are concerned about pyometra in your dog, contact the practice to make an appointment on 01626 835002.