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Thickening of the Uterine Lining and Fluid Filled Sac in Cats


Pyometra and Cystic Endometrial Hyperplasia in Cats


The abnormal thickening (pyometra) of the uterus' lining can affect cats at any age, although it is more common in cats that are six years of age or older. Cystic endometrial hyperplasia, meanwhile, is a medical condition characterized by the presence of pus-filled cyst inside the cat's uterus, causing the endometrium to enlarge (also known as hyperplasia).


The prognosis is often positive for both conditions. However, if the cervix is closed, it can be a life threatening condition requiring immediate medical attention.


These two conditions can affect both dogs and cats. If you would like to learn more about how pyometra and cystic endometrial hyperplasia affects dogs, please visit this page in the PetMD health library.


Symptoms and Types


Signs may include:


  • Depression
  • Lethargy
  • Vomiting
  • Closed cervix
  • Vulvar (vaginal) discharge
  • Lack of appetite (anorexia)
  • Frequent urination (polyuria)
  • Abdominal distention (from an enlarged uterus)




One of the known causes of this condition repeat exposure to estrogen and progesterone. The formation of cystic endometrial hyperplasis is often progressive, often following the development of a thickened uterine lining.


Intact older female cats that have never given birth are at a higher risk pyometra or cystic endometrial hyperplasia.




Your veterinarian will perform an examination to review the type and severity of your cat's discharge, as well as to view whether the cervix is open or closed. X-rays and ultrasounds will be used detect the size of the uterus, and to determine if the cat is pregnant.





In many cases, treatment will be given on an outpatient basis. However, if the cervix is closed, the condition can be life threatening and immediate action will be required. The preferred treatment for this medical condition is a hysterectomy -- the removal of your cat's ovaries and uterus. Other options are available, but at a higher risk to the animal's wellbeing; these are only recommended for cats with a high breeding value.


A lavage of the uterus and surrounding areas will be performed to remove the pus and fluids, and to support the healing process. Antibiotics are often administered to fight off infection. Prostaglandins, meanwhile, are administered to control the cat's cell growth and control hormone regulation, and to cause the smooth muscles in the cat's body to contract.


Living and Management


Your cat will be released from medical care once its uterus has returned to normal size and there are no signs of fluids. Antibiotics should be administered for several weeks to prevent infection. It is normal for vaginal discharge to continue until the healing process is complete.




Allowing your cat to go through its heat (estrus) cycles without being bred has been shown to increase the incidence of this medical condition. Therefore, spaying your cat (or removing its ovaries) is the best form of prevention.



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