CANINE PYOMETRA

 

Pyometra is a disease mainly of middle-aged female dogs that have not been spayed. Pyometra follows a heat cycle in which fertilization did not occur. Typically, within two to four months after the cycle, the female starts showing signs of the disease. If veterinary intervention is sought early, prognosis is often positive, however, if the dog's cervix is closed, it can be a life threatening condition requiring immediate medical attention.

As the dogs body attempts to flush out the build up of waste products through the kidneys, she will drink excessive quantities of water, and urinate large amounts frequently. She will lick at her vaginal area while the cervix is still open and the uterus may discharge a white fluid. She may run a low grade fever and if blood work is done, she will show an elevated white blood cell count. As the uterus increases in size and weight, the dog shows weakness in the rear legs, often to the point where she cannot rise without help. As the dog enters kidney failure, she stops eating and becomes very lethargic.

Pyometra can often present within 12 weeks of oestrus and bitches which have mis-mated, and subsequently received the estradiol hormone injection to abhort puppies, are at increased risk of infection.

Signs may include one or more of the following:

Abdominal distention (from an enlarged uterus), Vulvar (vaginal) discharge, Closed cervix, Lethargy, Depression, Lack of appetite, Vomiting, Frequent urination, Constant grooming around the vaginal opening

Your vet will first likely ask questions about when your dog’s last season was, whether she has been cleaning herself more often around her vulva, and how she has been acting recently. They will examine your dog’s abdomen to check for swelling, and may perform an ultrasound examination. Dogs with pyometra usually have a severe elevation of the white blood cell count and often have an elevation of globulins (a type of protein often associated with the immune system) in the blood. The specific gravity (concentration) of the urine is generally low due to the toxic effects of the bacteria on the kidneys.

 

Since toxicity may develop very quickly in dogs with pyometra, it needs to be treated promptly. Dogs will receive intravenous fluids, usually for several days, and antibiotics. In most cases, the preferred treatment is a complete ovariohysterectomy (spay). This removes the ovaries, oviducts, uterus, and all associated blood vessels. These animals can be a surgical challenge because of their poor overall condition. In some females valued for breeding, prostaglandin and antibiotic therapy may be tried instead of surgery. The prostaglandin is given for 5-7 days and causes the uterus to contract and expel the fluid. In mild cases, when the cervix is still open and the fluid is draining, the success rate is excellent. This therapy should only be used in dogs 6 years of age or younger, who are in stable condition, and have an open cervix. Prostaglandins can have side effects, especially after the first dose, including restlessness, panting, vomiting, increased heart rate, fever, and defecation.

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.

The best prevention is to have all female animals spayed. If the animal is used for breeding, then spaying the animal after she is past her breeding years is highly recommended. Pyometra is a fairly common and serious problem and is just one of many compelling reasons to have your female pet spayed at an early age.


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.

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