Bacterial Infection (Metritis) of the Uterus in Cats

By PetMD Editorial on Feb. 10, 2009

Metritis in Cats

Metritis, a uterine infection that usually occurs within a week after a cat gives birth, is symptomized by an inflammation of the endometrium (lining) of the uterus due to a bacterial infection. It can also develop after a natural or medical abortion, miscarriage, or after a non-sterile artificial insemination. The bacteria that are most often responsible for infection of the uterus are gram-negative bacteria like Escherichia coli, which often spreads into the blood, causing a blood infection. The infection may lead to sterility, and if left untreated, septic shock, a lethal condition, may follow.

Symptoms and Types

  • Discharge from the vulva that smells bad; discharge with pus, or pus mixed with blood; discharge that is dark green
  • Swollen, dough-like abdomen
  • Dehydration (the skin stays tented for a few seconds when pinched)
  • Dark red gums
  • Fever
  • Reduced milk production
  • Depression
  • Lack of appetite
  • Neglect of kittens
  • Increased heart rate if the bacterial infection has become systemic


  • Difficult birth
  • Prolonged delivery, perhaps with a large litter
  • Obstetric manipulation
  • Retained fetuses or placentas
  • Natural or medical abortion, miscarriage
  • Natural or artificial insemination (rare)


Your veterinarian will perform a thorough physical exam, including a chemical blood profile, a complete blood count, an electrolyte panel, and a urinalysis. These tests will help your veterinarian to determine whether the bacterial infection has spread to the bloodstream, where the infection might have originated, and how dehydrated your cat is. You will need to give a thorough history of your cat's health, onset of symptoms, and possible incidents that might have preceded this condition.

Diagnostic tools, like radiograph and ultrasound imaging, will allow your veterinarian to visually examine the interior of the uterus for any retained fetuses or birth matter, excess fluid accumulation, and/or abnormal amounts of abdominal fluid production due to uterine rupture.

A sample of the vaginal discharge will also be taken for cytologic (microscopic) examination. A culture of both aerobic and anaerobic bacteria (bacteria that lives with oxygen, or without oxygen, respectively) will be used for identifying the bacterial populations present in the blood, and a sensitivity of the isolated bacteria will be performed so that the most appropriate antibiotic treatments can be prescribed.


Your cat will need to be hospitalized for fluid therapy, and for correction and stabilization of any electrolyte imbalances. If the infection has reached sepsis, your cat will also be treated for shock. Your cat will also need to be placed on broad-spectrum antibiotics until the bacterial culture and sensitivity results return from the lab; then, depending on the results, your veterinarian may switch your pet to the antibiotic best suited for eliminating the bacteria that are causing the infection.

If the metritis is not in an advanced stage, your cat will most likely respond to medical treatment. However, medical treatment does not always prevent the infection from progressing to a generalized abdominal infection and ruptured uterus. If future breeding is not planned, having your cat spayed is the treatment of choice. This solution is especially appropriate when retained fetuses or placentas are present in the uterus, when the uterus has ruptured, or when it is severely infected. Patients suffering from a long-term infection that is not responding to medical treatment may improve with a surgical cleaning of the uterus.

Living and Management

If your cat is nursing and has been diagnosed with a bacterial blood infection, it will be better to hand-raise her kittens so that transmission of the infection through her milk can be prevented. This can also prevent possible harm to the kittens from exposure to the prescribed antibiotics in their mother's bloodstream. Keep in mind that even without spaying, animals that have been treated for a uterine infection have a chance of becoming less fertile, or even infertile, making future breeding difficult or impossible.

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