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Pyometra in Dogs

Pyometra in female dogs is serious and life-threatening.

Pyometra in dogs is a dangerous infection of the uterus. It is an extremely serious condition that can result in death if it is left untreated.

Causes of Pyometra in Dogs

Each time an unspayed dog goes into heat, her uterine lining swells in order to prepare for a pregnancy. Sometimes, this engorgement persists and this is known as endometrial cystic hyperplasia. When the lining of the uterus is in this state, it is more susceptible to becoming infected. Bacteria that are normally in the vagina may ascend into the uterus and cause it to fill up with pus. Bacteria and the toxins that they produce cross the uterine wall and enter the bloodstream, causing systemic poisoning. The uterus will eventually die and rupture, releasing pus and tissue into the dog's body. Pyometra causes death if it is not treated.

Presentation and Signs of Pyometra in Dogs

Dogs with pyometra may have fairly non-specific signs of illness at first. It is important that, if you have an unspayed female dog, you always keep pyometra in mind. If your dog is acting ill, err on the side of caution by taking her to the veterinarian. The following signs are common in dogs with pyometra:

  • Signs of illness generally occur a month of two after a heat cycle (dogs usually have heat cycles about every six months)
  • Lethargy
  • Anorexia
  • Fever
  • Vomiting
  • Diarrhea
  • Increased water consumption
  • Increased urination
  • Abdominal pain
  • Abnormal discharge from the vulva (this does not occur in cases in which the cervix is closed, so it should not be relied upon to raise suspicion of pyometra)
  • Dehydration
  • Shock
  • Collapse

Breeds, Gender, and Ages Most Commonly Affected by Pyometra in Dogs

  • Pyometra only affects female dogs that are not spayed.
  • Females of any age, once they have started their heat cycles, are at risk for pyometra. However, middle-aged and older dogs develop pyometra more often than young dogs.
  • Some studies have identified an increased incidence of pyometra in the following dog breeds (Jeff Dennis, 2012):

    • Rough-coated collies
    • Rottweilers
    • Miniature schnauzers
    • Cavalier King Charles spaniels
    • Golden retrievers
    • Bernese mountain dogs
    • English springer spaniels

Diagnosis of Pyometra in Dogs

Diagnosis of pyometra can be accomplished through the following steps:

  • Veterinary examination and history: A dog that has recently been through estrus and is displaying some of the signs listed above may be suspected by your veterinarian to be suffering from pyometra. Your veterinarian may be able to feel an enlarged uterus during an exam.
  • Lab work: Dogs with pyometra may have an increased white blood cell count on a CBC blood test and may show white blood cells and bacteria on a urinalysis.
  • X-ray: An x-ray of the abdomen of a dog with pyometra may reveal an enlarged uterus. If the cervix is open, allowing the uterus to drain, this may not be as obvious. Also, if the condition is in an early stage, the uterus may not be large enough to visualize on an x-ray. Alternatively, the uterus may appear enlarged on an x-ray, but the cause could be a condition other than pyometra, such as early pregnancy or tumors.
  • Abdominal ultrasound: When performed by an experienced clinician, ultrasound is a very sensitive way of diagnosing pyometra while simultaneously ruling out many of the other causes of uterine enlargement.

Treatment of Pyometra in Dogs

  • The best treatment for pyometra in dogs is surgical removal of the uterus and ovaries (spay).

    • During pyometra, the uterine tissue is engorged with blood and more fragile than normal due to its breakdown by the bacterial infection. This type of tissue is called "friable," and it makes surgery more dangerous.
    • Because the dog is sick, the anesthesia and surgery are more risky than when a routine spay is performed on a healthy dog.
    • Surgery is the only treatment that eliminates the risk of future pyometra because the uterus is no longer present.
    • Surgery is the only treatment for pyometra that is sure to resolve it, if the animal is able to withstand anesthesia, surgery, and recovery.
  • If a dog is very valuable to a breeding program and is in stable condition, an attempt could be made to save her uterus and ovaries through prostaglandin treatment.

    • Prostaglandin, a hormone that causes the uterus to cramp, is given through injections to help empty the pus from the uterus.
    • The dog is hospitalized during this treatment, and some discomfort will accompany the process. Other likely side effects are vomiting, drooling, anxiety, panting, and increased heart rate.
    • If the dog's cervix is closed, a lower dose of prostaglandin is given first to relax and open it.
    • Alternatively, a different medication, a dopamine agonist, can be used concurrently with prostaglandin to open the cervix.
    • Following prostaglandin treatment for pyometra, the dog must become pregnant during the next heat cycle or her chances of developing pyometra again are close to 80%.
    • The uterus is often scarred after a bout of pyometra, so the dog may not be able to carry a normal pregnancy.
    • This treatment should not be considered in severely ill dogs because the delay between treatment and improvement may be too long.
    • This treatment should only be performed by a veterinarian, under strict monitoring conditions. Surgery may need to be pursued quickly if the dog worsens.
  • A third treatment option, also used if a dog is very valuable for breeding and is in stable condition, is surgical drainage and lavage (the washing out of an organ or body part).

    • During this treatment, the dog is anesthetized and a catheter or pipette is passed through the cervix and into the uterus in order to drain it of pus. The uterus is then flushed with one of two solutions.

      • One solution that is used is saline containing prostaglandin. The prostaglandin works to cause cramping in the uterus, to further empty it.
      • The second solution that is used is povidone-iodine, a cleanser, and an injection of prostaglandin is given concurrently. Uterine drainage and lavage is a specialized treatment, and it may be necessary to seek out a veterinarian who works with a high number of breeding animals to perform it.

Home Care of Pyometra in Dogs

Sometimes, in the case of an "open pyometra" where the cervix is open and the uterine contents are draining, antibiotic therapy can control the infection and possibly resolve it. However, this is not a preferred treatment for two reasons:

  • The pyometra may not be resolved with this method, and the dog will become sicker and less stable during the time that it is being attempted. This decreases the dog's prognosis for recovery because surgery becomes more risky as the condition goes on.
  • Dogs that have suffered from pyometra once are over 70% likely to develop it again after subsequent heat cycles.

Prevention of Pyometra in Dogs

Pyometra is prevented by having your female dog spayed before she goes into her first heat. Generally, dogs experience their first estrus cycle around seven months of age, so dogs that are spayed at around six months of age generally never go into heat.

Reasons that people do not have their female dogs spayed:

  • Cost: The cost of a spay surgery may cause some people to avoid or postpone it. However, the cost and risk of a surgery when a dog has pyometra are both much higher. Also, dogs that are spayed before their first heat are at a much lower risk of developing mammary (breast) cancer, an aggressive and often deadly condition, later in life.
  • Wanting to have a litter: Some people do not have their female dogs spayed because they would like to have a litter of puppies. Please keep in mind that there is an overpopulation of dogs in the US, and many thousands of dogs are euthanized each year as a result. While you may find homes for all of the puppies in your litter, it will decrease the number of homes available for shelter dogs. Also, dogs do have trouble giving birth sometimes and require C-sections, which are costly and can be dangerous.
  • People associate it with having a sterilization surgery themselves: This occurs more with male dogs than female dogs, but sometimes owners don't want to take away a dog's "femininity" by spaying her. It's important to remember that dogs are not humans, and they do not have the same psychological concerns. Spaying your dog is healthier for her and better for the dog population in general.

Prognosis for Pyometra in Dogs

If a dog is already in shock by the time the pyometra is diagnosed, the prognosis is poor. If the pyometra is caught early, the dog is well-supported with fluids and temperature stabilization before and after surgery, and no complications occur during surgery due to the fragile uterine tissue, the prognosis is good for full recovery. Relapse will not be possible.


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