This condition forms the perfect breeding ground for bacteria, which eventually leads to infection. The thickened uterine lining also prohibits invaluable white blood cells from entering the uterus to fight the infection while simultaneously preventing the uterine muscles from discharging the accumulated fluids. Cystic endometrial hyperplasia warrants immediate veterinary attention as it can be life-threatening. This condition is more commonly diagnosed in dogs, but may also occur in cats as well.

Cystic endometrial hyperplasia is a condition in sexually intact female cats typically associated with pyometra. Pyometra occurs as a result of hormonal changes in the uterus. After an estrus cycle, progesterone levels increase and the lining of the uterus begins to thicken to prepare for pregnancy. If the cat does not become pregnant after several cycles, the uterine lining may continue to thicken, causing cystic endometrial hyperplasia.

Some cats may not show any symptoms in the first stages of the disease. For the best prognosis, you will need to take your cat to the vet as soon as you notice any of the following symptoms:

The primary cause of cystic endometrial hyperplasia in cats is the hormonal changes in the uterus following estrus. When a female cat is not in estrus, her cervix remains closed. The cervix opens during estrus so that sperm can enter. Progesterone levels are also increased, which prevents white blood cells from entering the uterus so they won’t treat sperm as an infectious foreign body. 

When the cervix opens, bacteria can enter the uterine lining, contributing to infection. The pus associated with cystic endometrial hyperplasia creates an environment that is perfect for bacteria to reproduce. The cervix may close following the development of cystic endometrial hyperplasia, preventing discharge from draining. If this happens, the cat will become severely ill, and is more likely to experience vomiting and/or diarrhea.

Another cause of cystic endometrial hyperplasia is the administration of hormones, particularly progesterone, to treat other reproductive conditions.

Your vet will first perform a thorough physical examination. You should let your vet know how long your cat has been experiencing symptoms, as well as any previous history of reproductive disorders.

Your vet will utilize standard diagnostic methods, including complete blood count, blood chemical profile, ultrasound, and urinalysis to rule out other reproductive disorders and pregnancy. Your vet will perform an abdominal x-ray to confirm pyometra if the cervix is closed. Your vet may also test the vaginal discharge, if present, using vaginal cytology. 

Treatment may vary depending on the severity of the pyometra as well as owner preferences in regards to future breeding. For most cases of pyometra, the treatment of choice is to spay the cat. This works particularly well in mild cases or in cats that have been diagnosed in the early stages of the disease.

For more severe cases of pyometra, surgical correction will be more invasive and may require hospitalization. Intravenous fluid therapy will be administered during hospitalization, and fluid imbalances will be corrected before surgery is performed. Your vet will prescribe an antibiotic regimen for up to two weeks following surgery.

For owners who hope to breed their cat in the future, prostaglandin drug therapy may be recommended for animals younger than eight years old. However, this medication has not been approved by the FDA for use in cats or dogs, and may cause adverse side effects.

Recovery and prognosis but is generally good in cats that had an open cervix at the time of diagnosis. The prognosis in cats with a closed cervix at the time of diagnosis is guarded.

Following surgery, ensure your cat does not irritate the surgery site. An Elizabethan cone can assist with this. Check the surgery site daily to ensure no swelling or pus has occurred. Contact your vet immediately if there is swelling or pus near the surgery site. You should always administer antibiotics for the full duration of treatment even if your cat’s condition begins to improve. Failure to do so may result in aggressive recurrence.

For cases resulting in a spay procedure, your vet will schedule follow-up appointments as needed to ensure proper healing. In cats receiving prostaglandin therapy, follow-up appointments will be scheduled every two weeks. Your vet will advise you on breeding your cat following completion of the prostaglandin therapy.