Pyometra is a serious and potentially life-threatening bacterial infection of the uterus that primarily affects unspayed female dogs and cats. The term “pyometra” comes from the Greek words for “pus” and “uterus,” accurately describing how the uterus fills with pus due to infection. This condition is most common in middle-aged to older females, often developing one to two months after a heat cycle, and can progress rapidly if not treated promptly. While more frequently reported in dogs, cats can also be affected, though their symptoms may be subtler. Early recognition and veterinary intervention are crucial to prevent severe complications, including sepsis or organ failure.
What Causes Pyometra
Pyometra develops due to hormonal changes in the reproductive cycle of unspayed females. After estrus (heat), progesterone levels rise, causing the uterine lining to thicken in preparation for pregnancy—a process known as cystic endometrial hyperplasia (CEH). If pregnancy doesn’t occur, this thickened lining can create an ideal environment for bacterial growth. Bacteria, most commonly Escherichia coli (E. coli), ascend from the vagina into the uterus when the cervix is relaxed during heat. Other bacteria like Streptococcus and Staphylococcus may also be involved.
There are two types of pyometra: open and closed. In open pyometra, the cervix is open, allowing pus to drain out as vaginal discharge. In closed pyometra, the cervix is sealed, trapping the infection inside, which can lead to a distended abdomen and more severe systemic effects. Factors like repeated heat cycles without breeding, age, and in rare cases, hormone treatments (e.g., estrogen injections to prevent pregnancy) increase the risk.
Signs and Symptoms
Symptoms of pyometra can be subtle at first, especially in cats, but they often worsen quickly. Common signs include:
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Lethargy and depression: Your pet may seem unusually tired or uninterested in activities.
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Increased thirst and urination (polydipsia and polyuria): This occurs as the body tries to flush out toxins.
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Vaginal discharge: Often bloody, pus-like, or foul-smelling in open pyometra; absent in closed cases.
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Loss of appetite (anorexia) and vomiting: Pets may refuse food and experience gastrointestinal upset.
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Swollen or painful abdomen: Due to the uterus filling with pus.
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Fever or pale mucous membranes: Indicating infection or anemia.
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Excessive licking of the vulva: Common in both dogs and cats.
In advanced cases, pets may collapse, develop tachycardia (rapid heart rate), or show signs of shock. Cats might exhibit unkempt fur or hide more than usual. If you notice any of these signs, especially after a recent heat cycle, seek veterinary care immediately.
Diagnosis
Our veterinarians diagnose pyometra through a combination of history, physical examination, and diagnostic tests. A swollen uterus may be palpable, and bloodwork often reveals elevated white blood cells, anemia, or kidney issues from toxins. Ultrasound is the gold standard for confirming an enlarged, fluid-filled uterus. X-rays can also show uterine enlargement, and vaginal cytology may identify bacteria or pus.
Treatment Options
Pyometra is a medical emergency, and the standard treatment is surgical removal of the uterus and ovaries (ovariohysterectomy, or spay surgery). This eliminates the source of infection and prevents recurrence. Surgery is performed under anesthesia, with antibiotics and fluids administered to stabilize the pet.
In rare cases, medical treatment with prostaglandins (to contract the uterus and expel pus) and antibiotics may be attempted for breeding animals, but it’s riskier and not always successful. For cats, surgery is preferred, though prostaglandins can be an option if fertility preservation is needed. Without treatment, pyometra can lead to uterine rupture, peritonitis, and death.
Prevention
The most effective way to prevent pyometra is to spay your female dog or cat before the condition develops. Spaying removes the ovaries and uterus, eliminating hormonal influences and infection risk. Routine veterinary check-ups and avoiding hormone therapies unless necessary can also help. If your pet is intended for breeding, consult with one of our veterinarians about safe practices, but spaying after breeding is complete is recommended. Bingle Vet provides spaying services and advice tailored to your pet’s needs.
Conclusion
Pyometra is a preventable yet dangerous condition that underscores the importance of spaying unbred female pets. By recognizing early signs and acting swiftly, pet owners can save their companions from this life-threatening infection. Always consult a veterinarian if you suspect pyometra—prompt care can make all the difference in ensuring a healthy, happy life for your furry friend.