By Dr. Becker
Today I’d like to discuss pyometra, or uterine disease in female pets.
Pyometra occurs most commonly in intact female dogs that have not been pregnant. But it is also seen in unspayed cats, hamsters, ferrets, guinea pigs, rats, and rabbits. The problem can occur at any age, but is usually seen in dogs who are six years of age or older.
More Than a Uterine Infection
It was once thought pyometra was just a uterine infection. But the condition is now recognized as a hormonal abnormality with or without the presence of a secondary bacterial infection. It can be life-threatening if it’s left untreated.
Pyometra is triggered by a heat cycle that doesn’t end in egg fertilization. Dogs typically start showing signs of the disease within two to four months after the heat cycle. Either an excessive amount of progesterone or hypersensitivity of the uterus to progesterone is what causes the condition.
Cysts develop in the lining of the uterus and release large amounts of fluid into the uterus. The accumulated fluid can spark a secondary bacterial infection.
‘Open’ and ‘Closed’ Pyometra
A normal uterus in an average-sized dog weighs just a few ounces. But when pyometra is present, the organ can weigh up to four pounds due to the accumulation of fluid and diseased tissue.
The fluid accumulation in the uterus starts leaking out through the vagina. The dog’s natural response is to lick the area clean. Excessive licking can introduce still more bacteria through the cervix and into the uterus.
The body’s response to the secondary infection is to increase fluid production and white blood cells to the uterus, which continues to flow out of the vagina. This is called an open pyometra, because the cervix is open, allowing fluid and accumulated debris to be flushed from the body through the vagina.
At some point, the cervix closes and the fluid can no longer flow out of the uterus. Meanwhile, the body continues to produce more and more fluid and white blood cells. The result is an enlarged uterus. This condition is called closed pyometra, because the cervix does not allow the accumulated material to exit through the vagina.
In worst-case scenarios, the uterus can rupture and empty all of its contents into the abdominal cavity. When this happens, the animal usually dies of septic peritonitis and/or acute kidney failure from uremic poisoning within about 48 hours, even with very aggressive medical intervention.
Obviously, the goal is to catch this condition long before it becomes this serious. Catching symptoms early on is very important in treating pyometra successfully.
Symptoms of pyometra can include lethargy, depression, fever, lack of appetite, vomiting, excessive thirst, frequent urination, a distended abdomen (due to the enlarging uterus), vaginal discharge and excessive licking at the area, as well as weakness in the rear limbs due to the enlarged uterus.
Remember: these symptoms will be noted after a heat cycle. If your female dog has recently concluded a heat cycle and you begin to see some of these symptoms, you should seek care immediately.
Diagnosis and Treatment of Pyometra
Pyometra is diagnosed with an examination of the cervix and vaginal discharge, plus X-rays and/or an ultrasound to evaluate the size of the uterus and to rule out pregnancy.
Toxicity can develop rapidly in a dog with pyometra, so prompt treatment is really a very important part of successful treatment, especially if the cervix has closed. The preferred traditional treatment for pyometra is spaying. If the owner wants to breed the animal, obviously other options are available, but they present a higher risk to the dog. IV fluids are usually administered for several days, along with antibiotics to treat the potentially life-threatening infection. The uterus and surrounding areas will be irrigated to flush away pus and fluids, and to speed healing.
In cases of open pyometra, prostaglandins are sometimes administered to control cell growth, regulate hormone production, and cause contraction of the uterus to help expel accumulated fluid.
Why Dogs with Pyometra Should Be Spayed
Since pyometra is most commonly seen in middle-aged or older intact female dogs who have never been bred, this actually IS a condition that can be prevented by spaying your dog, unlike breast cancer, which has historically been touted as the most important reason to spay dogs.
Those of you who are subscribers to this site know that I certainly advocate rescuing pets. Whenever possible, it’s important to prevent any type of unplanned pregnancy. If you plan to breed your dog, I hope you are an experienced, knowledgeable, and ethical breeder who selects for health first and foremost. This also means putting the health of a cycling female before the desire to perpetuate a certain strain of DNA.
All that to say, I strongly recommend spaying a dog with pyometra to avoid recurrence of the disease following future heat cycles.
If you’re like most pet owners who don’t intend to ever breed their dog, before you have your pet spayed at an early age – let’s say, six months – I encourage you to learn about surgical sterilization options and the risks and benefits associated with each of them.
If you decide to spay your dog, holding off on the surgery until she is sexually mature and fully mentally and physically developed can help protect her against many forms of cancers and endocrine diseases later on.