Pyometra

What is a pyometra?

This is a potentially life threatening condition which requires immediate veterinary treatment.

Pyometra is an infection of the lining of the uterus which often occurs shortly after oestrus (heat or season). Following a normal oestrus, progesterone levels remain increased for 8-10 weeks to prepare the uterus lining for a potential pregnancy.
If pregnancy does not happen, the progesterone levels do not return to normal and the lining continues to thicken, forming cysts. These cysts produce fluid which creates the ideal environment for bacteria to develop.

The cervix, which is the entrance to the uterus, usually remains closed unless oestrus is occuring. While the cervix is open, bacteria which normally live in the vagina will enter the uterus. Normally these bacteria won’t survive, but in a thickened uterus with the ideal environment created for bacteria they will thrive. Due to the thickening of the uterus it is also unable to contract fully and expel the bacteria.

Pyometra can occur in any unneutered dog or cat. It is more commonly seen in middle aged to older dogs, although young dogs are also susceptible. It occurs rarely in cats.

Older dogs which have had many oestrus cycles without a pregnancy, have the perfect uterine wall to promote this disease. It usually occurs 4-8 weeks after oestrus.

Clinical signs

These can vary considerably so you should always seek veterinary treatment.

  • Lack of appetite
  • Increased thirst
  • Lethargic
  • Temperature

If the cervix is open allowing drainage you will see a pussy, vulval discharge which is usually foul smelling. Your dog will often be continually cleaning her back end. This is called an open pyometra.

If the cervix is closed the pus continues to build up without draining causing the dog to become seriously ill, extremely quickly.

Diagnosis

A full clinical examination is performed by your veterinary surgeon. Pyometra is often suspected if the dog is not neutered, drinking more and has a vulval discharge, 4-8 weeks after oestrus. A blood sample may be collected and X-rays or an ultrasound scan may be performed to confirm the diagnosis.

Treatment

The most recommended option for treatment is surgery to remove the infected uterus and ovaries- an ovariohysterectomy or spay. Depending on the severity of the infection, your dog may need to be stabilised first using intravenous fluids and antibiotics, prior to surgery. Although the surgery being performed is a neutering operation, the surgery is much more complicated due to the enlarged and weakened uterus. It must be removed without rupturing to prevent the pus from leaking into the abdomen. Additionally there is always an increased anaesthetic risk when the patient is unwell. This is one of the reasons why veterinary surgeons always recommend spaying your dog at an early age when they are young, fit and healthy!

Medical treatment for pyometra is possible using injections containing prostaglandins which reduce the progesterone levels. This causes the cervix to open and expel the pussy contents of the uterus. Medical treatment for pyometra can be expensive especially in large dogs. It is not always effective and surgery may still be necessary.

Medical treatment can be considered for young bitches from whom the owner would like to consider breeding from at subsequent seasons. It can also be considered for older bitches where general anaesthesia and surgery is considered inadvisable.

Your veterinary surgeon will discuss the best course of treatment for your pet. If you do not seek any treatment for your pet suffering from a pyometra the outcome will potentially be fatal.