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Pyometra is a disease which occurs in intact (un-spayed) female dogs and cats. Pyometra means that the canine or feline reproductive tract, primarily the uterus, fills and distends with infection and pus. The presence of this infectious material makes the pateint very sick, and left untreated is imminently fatal. Any unspayed dog or cat can develop pyometra, but it seems to be especially prevalent in pets that are 7 years or older.

The cause for pyometra in dogs and cats is due to a combination of factors. Abnormal mucus build-up in the uterus, combinedwith abnormal hormone fluctations hormone fluctuations leads to bacterial proliferation within the canine or feline reproductive tract. As the infection progresses, the uterus fills and distends with pus. Death occurs from pyometra when the uterus ruptures and the toxic material spills into the abdomen, causing peritonitis. Death can also occur by the infection spreading to the bloodstream, a condition know as sepsis; or from severe dehydration leading to hypovolemic shock.

Pyometra typically begins to manifest 4-8 weeks following a dog or cat’s heat cycle. Patients with pyometra sometimes have pus discharge from the vagina, become lethargic, do not eat, and drink excessive amounts of water.

Pyometra is diagnosed through a combination of history, examination, and abdomenal x-rays. The typical x-ray of a patient with pyometra illustrates distended, sausage-like loops of uterus. If there is any ambiguity or poor detail on the abdomenal x-ray making it difficult to confirm the diagnosis of pyometra, then abdominal ultrasound should be considered, as it provides greater soft tissue detail.

Treatment for pyometra is surgical, as the disease does not repond to antibiotics. Essentially, a spay has to be performed. However, a pyometra spay is considerably more challenging than a routine spay. Special care has to be taken so that the stretched out and easily breakable uterus does not rupture and spill its poisonous material into the sterile abdomen. This makes the procedure considerably more time consuming, with the already compromised patient having to remain under anesthesia for a longer period of time. The patient should also be hospitalized and kept on IV fluids and antibiotics for a few days until she is stable and starts eating. Following discharge, I typically recommned that a patient remain on antibiotics for an additional 2-3 weeks.

Generally speaking, pyometra carries a favorable prognosis in cases where the uterus is successfully removed without any spillage of its toxic material into the abdomen, provideded there was no sepsis or organ compromis prior to the surgery. In cases of spillage, however, the prognosis is guarded, usually necessitating a prolonged stay in the hospital.

The best way to deal with pyometra is prevention. Spaying your dog or cat effectively eliminates the possibility of pyometra, while effectively preventing mammary cancer, difficult pregnancy, and heat based aggression.


By: Roger L. Welton, DVM
Founder, Web-DVM
President Maybeck Animal Hospital
Author Canine and Feline 101

18 thoughts on “Pyometra

  1. Shannon says:

    A stray cat I recently brought to a clinic died one day after the pyometra surgery. She was fine after surgery and died the next day. If the cat had peritonitis wouldn’t they have known that before/during/after surgery? Is it likely that the cause of death was sepsis? Obviously the cat’s life was the most important thing. Since there is nothing I can do for her at this point I’d really like to know the cause of death.

  2. Steve says:

    I highly recommend female dogs and cats be spayed. My 7 year old Chihuahua became sick two days ago. She became lethargic and would not eat. I thought this may have had to do with a heat cycle, because it is normal for her to not eat much during this time. I gave her Clavamox, but it did not help. On 7/27/17, she would barely move and I took her to the vet and was told it was most likely Pyometra. The doctor came out a few minutes later and told me she had died on the table, but they were trying to get her back with CPR. I was told her brain was most likely swelling and she would not respond with her eyes. I told the vet to let her pass peacefully rather than she suffer. The doctor then came back and told me she was breathing on her own again. The doctor said she had about a 10-15% chance of pulling through. This slim chance was both at the vet and home. I chose to bring her home with an IV provided by the doctor along with Prednisone. About four hours later, she passed away. My heart was broken as well as my wife and children. She passed away in the presence of her family rather than in the animal hospital. Bottom line, have your dog or cat spayed. Don’t let this happen to your pet. This is a sudden and deadly illness.

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