What is pyometra in dogs?

Pyometra, also known as a pyo, is an infection of the uterus (womb).  It’s a common condition in female dogs who haven’t been spayed and requires urgent veterinary treatment.

Each time a female dog has a season — usually about twice a year — she undergoes all the hormonal changes associated with pregnancy. This is regardless of whether she becomes pregnant or not. The changes in the uterus that occur during each season make infection more likely with age. A very common organism called E. coli, found in your dog’s faeces, usually causes pyometra. Injections with some hormones, either to prevent seasons or for treatment of other conditions, can increase the risk of the condition developing.

Signs and diagnosis

Pyometra symptoms

Pyos are only seen in females as males do not have a uterus. The signs usually develop around four to six weeks after the female has finished bleeding from her last season. In some cases, the bitch may appear to be having a prolonged season.

The early signs of pyometra can include unusual tiredness, lack of appetite and an unquenchable thirst. These may also be followed by vaginal discharge. In the latter stages, your dog may be reluctant to move. If left untreated these signs will worsen to the point of dehydration, collapse and death from septic shock.

If you see any of these signs in a female dog who hasn’t been neutered, you should contact your vet straight away or, out of hours, your nearest Vets Now pet emergency clinic or 24/7 hospital.


How is pyometra diagnosed in dogs?

Your vet will probably suspect your dog has a pyo based on your description of the signs and from their examination of your pet.

They may suggest procedures such as ultrasound and blood tests to confirm the diagnosis, rule out other possible causes, and to check your pet is well enough to undergo treatment.

Image of a dog for Vets Now article on pyometra in dogs
Most dogs will make a full recovery after treatment for pyometra if the condition is caught early

Can I prevent pyometra?

Most dogs will make a full recovery after treatment if the condition is caught early. Spaying your dog before she develops a pyo will prevent this condition occurring.

If left untreated, or if the dog has had a pyometra for a while before arriving at the vets, she may be septic (bacteria has gone into the bloodstream) and a longer period in hospital may be required. In this situation, the prognosis is usually worse.

Can a spayed dog get pyometra?

Dogs who have been spayed may still be at risk if the operation to remove the ovaries and the uterus hasn’t been carried out correctly, a portion of the ovarian tissue is still present, or they have been administered progestational hormones.

Treatment options

Treatment for pyometra in dogs

Treatment typically involves surgery to remove the uterus. The operation is essentially the same as a routine spay.

However, there is more risk involved and a higher chance of complications when the operation is being carried out on a sick pet. Your dog will also be given intravenous fluids (a drip), antibiotics and pain relief.

Alternative treatment for pyometra

Medical treatment using prostaglandins — hormones — along with antibiotics, is theoretically possible but rarely chosen. Risks and limitations of treatment with prostaglandins are:

  • it’s only possible with an “open pyometra”, where pus is draining from the vulva — in a “closed pyometra” case where the cervix is closed treatment carries a risk of rupture and peritonitis (infection in the entire abdomen)
  • it often results in signs of distress including restlessness, panting, vomiting, defecation, salivation, and abdominal pain
  • it usually takes at least 48 hours for any noticeable improvements
  • if your dog is severely ill at the time of diagnosis, she may die from blood poisoning before the prostaglandins have a chance to work
  • the recurrence rate is high — around 60%
  • your dog’s fertility will be affected — successful breeding only occurs in a small number of dogs following treatment