Canine Pyometra: Uterus Infection in Dogs

Pyometra is a condition that may affect female dogs. The infection of the uterus is more frequent in older canines, but the infection may affect dogs of any ages. Spayed dogs are typically not affected by pyometra.

Causes of Pyometra

Pyometra is an infection that is caused by Escherichia coli, which is a bacterium that is normally present in healthy amounts in the uterus of the dog. When there is an overgrowth of the Escherichia coli bacteria, the uterus infection occurs; this may be 2 months after the estrus.  

The uterus infection may be due to the administration of high amounts of estrogen or progesterone.

Symptoms of Pyometra

Typically, the symptoms of pyometra will occur 1 to 2 months after the dog was in heat. If progesterone or estrogen is administered to your pet, she may also develop a uterus infection following this treatment.

If your dog is affected by pyometra, she will display a number of symptoms:

  • Fever
  • Vaginal discharge, which is thick and contains pus; the discharge may contain blood
  • Lack of appetite
  • Lethargy
  • Increased thirst
  • More frequent urination
  • Dehydration
  • Septicemia, shock and collapse, if the infection causes the cervix to close

Some dogs may not show any symptoms at all, except for the vaginal discharge.

Diagnosis of Uterus Infection

The pyometra may be detected by palpating the uterus, which will be enlarged and thickened.  If the cervix is closed, the vet will perform blood tests.

The vaginal discharge should also be tested and the tests will show the presence of the Escherichia coli bacteria.

The vet will want to know about the date of the last heat cycle (estrus) or if your dog has received estrogen or progesterone.

The vet will establish if there are signs of septicemia. The white blood cell count will be elevated in dogs with septicemia.

Treatment Options

Pyometra should be treated as soon as possible, as this condition may advance and cause complications.

The typical treatment for the uterus infection is the removal of the uterus and the ovaries. However, if the pet is used for breeding purposes or if the cervix is closed, the vet will prescribe antibiotics for at least 10 days. When the cervix opens, the vet will recommend surgery.

If the dog is severely dehydrated, the vet will also recommend fluid therapy.


After surgery, the prognosis is favorable. Over 90% of treated dogs will get back to normal, but will not be able to breed. However, if the cervix is closed and the infection has spread to great parts of the abdomen, there may be complications.

Dogs treated with antibiotics have a great chance of recovery as well.

Prevention of Pyometra

Pyometra may be prevented by spaying the dog as early as possible. The occurrence of uterus infections in neutered dogs is minimal.

The administration of estrogen or progesterone must also be avoided to prevent uterus infections.

In dogs treated with antibiotics that still have the uterus and ovaries, pregnancy can prevent the re-occurrence of the uterus infection.