Pyometra is a bacterial infection of the uterus that mostly occurs in middle-aged or older unspayed female dogs, though it may also occur in cats or young dogs. It can result in the accumulation of infection in the bloodstream or abdominal cavity, which can rapidly lead to systemic infection, shock, and death. The severity of symptoms varies depending on whether the female’s cervix is open or closed.
Signs & Symptoms of Pyometra
- Drinking and urinating a lot
- Lack of appetite
- Abdominal pain and enlargement
- Constant grooming around the vaginal opening
In the case of an open cervix, a thick, bloody, foul-smelling discharge draining from the vaginal opening is the first sign of an infected uterus. These dogs tend to appear less sick because the infection has a route to leave the body.
If the dog’s cervix is closed, there will be no discharge and the infection can accumulate and spread into the bloodstream or enter the abdominal cavity. Symptoms can progress to those of shock, including a high fever and rapid pulse. The uterus will fill with pus and expand. Infections of other organs is common. The sick dog will need veterinary attention immediately.
Causes of Pyometra
The root cause of pyometra is heightened levels of progesterone, either found naturally in the four to eight weeks after a heat cycle, or induced by hormone-based therapies such as those used to prevent unwanted litters. The hormone estrogen is used in some of these "abortion" therapies, which, if given at a certain point after the heat cycle, can increase the effects of progesterone even further (though most of these therapies have been taken off the market). These high progesterone levels can cause cysts and pockets, which are prime target locations for bacteria. In pyometra cases, Escherichia coli (E. Coli) has been the most common bacteria isolated from the infected uterus due to its ability to thrive in a uterus sensitized by progesterone.
Diagnosis of Pyometra
Diagnosis begins with a complete history and a physical exam. Your veterinarian will most likely do the following:
- History - Look at the dog’s spay history to see if she is intact.
- CBC/Chemistry Panel - These blood tests will evaluate various internal organ functions, including the heart, liver, kidneys, pancreas, metabolism, and electrolyte balance. The CBC is a measure of the amount and different kinds of red and white blood cells that are present in the body.
- Discharge cultures - Your veterinarian will take a swab of the discharge secreting from your dog’s vaginal opening. This sample will be transferred to a slide and examined under a microscope.
- Radiographs - These will show a distended uterus that displaces other organs in a closed cervix case.
- Ultrasound - Taking an ultrasound of the uterus will show infection or a distended uterus in a closed cervix case.
- Urinalysis - This may help rule out other causes of increased water intake and urination, as well as diagnose any secondary bladder infections.
Treatment for Pyometra
The bacterial infection cannot be resolved until the infected fluid is removed from the dog’s body, either by removing the uterus or draining the infection. In most cases, it is best to have the infected uterus removed by spaying the dog, taking special care not to rupture the uterus and release infection into the body cavity. After the uterus is removed, the dog will most likely be put on antibiotics for one to three weeks to clear up any remaining infection.
In cases where the dog is intended to be bred in the future, treatment with intravenous fluid therapy and antibiotics may help alleviate the problem. If the cervix is closed and removal of the uterus is not desired, a hormone-like compound called prostaglandin can be given to relax the cervix in an attempt to drain the infection. However, in unspayed dogs that have had pyometra before, there is a high risk of recurrence.
Prevention of Pyometra
The best way to prevent pyometra is to spay all female dogs at a young age or at the end of their breeding career.
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