Canine Endometritis

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Canine endometritis, or cystic endometrial hyperplasia, is a uterine condition that affects older, intact female dogs. It causes a thickened uterine wall. While many dogs have endometritis but never show symptoms or develop complications, others develop bacterial infections in the thickened wall, leading to pyometra, a condition that can be fatal if left untreated.



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After a dog's estrus, or heat cycle, she enters a period called diestrus. During diestrus, her body releases progesterone whether she is pregnant or not. Progesterone causes the uterine wall to thicken. With each estrus cycle that does not result in pregnancy, the uterine lining builds. The increased thickness makes it a prime location for bacteria to grow. As the bacteria grow, the wall becomes cystic and secretes bacteria-filled fluid, or pus. Once a bacterial infection establishes, the diagnosis is pyometria.



In addition to the introduction of bacteria to the thickened lining during diestrus, causes of endometritis can include difficult births that introduce bacteria, retained placentas, retained fetuses and progestational drugs.



During diestrus, the cervix is open, allowing bacteria to enter through the vulva. Once the bacteria enter and grow inside the uterus, pyometria is diagnosed. Pyometria breaks down into two different types -- open and closed. In open pyometria, the cervix is open and the bacteria, or pus, discharge through the vulva. In closed pyometria, the cervix closes, trapping the bacteria in the uterus and creating a life-threatening condition whereby the uterus can rupture, sending bacteria into the abdominal cavity and spreading throughout the bloodstream.



The main symptom of endometritis is a noticeable vaginal discharge. When it progresses to pyometra, symptoms include an increased abdomen, lethargy, depression, reduce appetite, vomiting and frequent urination.



The main treatment for endometritis and pyometra is an ovariohysterectomy, or spaying. This removes the infection and prevent further occurrences. Treatments with the hormone PGF2 offers a nonsurgical option for breeding females, however, this treatment does not come without risk. The hormone helps to expel the uterine lining and bacteria. In cases of closed pyometra, this can cause the uterus to rupture. With hormone treatment, it is likely the dog will become infected again.


By Deborah Lundin

Enpevet: Dog: Endometritis
VetInfo: Cystic Endometrial Hyperplasia in Dogs
American Kennel Club Canine Health Foundation: Pyometra
PetMD: Thickening of the Uterus Lining and Fluid-Filled Sac in Dogs


About the Author
Deborah Lundin is a professional writer with more than 20 years of experience in the medical field and as a small business owner. She studied medical science and sociology at Northern Illinois University. Her passions and interests include fitness, health, healthy eating, children and pets.

Always check with your veterinarian before changing your pet’s diet, medication, or physical activity routines. This information is not a substitute for a vet’s opinion.


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