What Is Pyometra in Dogs? Signs, Symptoms and Treatment 

Updated June 21, 2022
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Dogs are not necessarily known for smelling like roses, but if your unspayed female dog suddenly gives off a fishy or unpleasant smell, they could have a pyometra. Pyometra is an infection of the uterus, which can be fatal when not treated promptly. If you notice a foul, horrible smell coming from your dog or pus-like vaginal discharge, it's important to learn more about the signs of pyometra so you can give your pet the care they need.

What Is Pyometra?

Pyometra (pyo- meaning "pus," and -metra meaning "uterus") is a life-threatening infection of the uterus. It can affect any unspayed female regardless of whether they have been bred. However, it is most common in dogs between the ages of 6 and 10 years who have not had a litter. Studies suggest that approximately one in four intact female dogs under the age of 10 years old will develop a pyometra.

Canine pyometra is most likely to begin between two and eight weeks after a dog's heat cycle. This happens because relaxation of the cervix during estrus can allow bacteria to enter the uterus. Additionally, hormonal changes in a dog's body during heat prepare the uterine lining for pregnancy, which creates an ideal environment for these bacteria to grow. The infection will progress until the uterus fills with harmful pus. You may not notice any apparent signs of the condition until a few months after the heat cycle.

Types of Pyometra Infections

Based on the origin of the infection and presenting signs, there are generally three types of canine pyometra.

Closed Pyometra

The term "closed pyometra" refers to the condition when the infection develops inside the closed uterus. The cervix remains closed and traps pus within the uterus. This type of pyometra is especially dangerous, as it often takes longer to notice signs of illness. However, dogs with a closed pyometra may become sicker more quickly than if their pyometra is open.

Open Pyometra

The term "open pyometra" is used to describe the condition when the cervix is slightly open, so some pus is able to escape from the uterus. Even though the infection is not completely trapped within the uterus, this type of pyometra is still life-threatening to dogs. An open pyometra is easier to diagnose because there are visible signs of infection, such as a foul-smelling discharge released from the vulva.

Pyometra in Spayed Dogs

Unfortunately, pyometra can occasionally occur in dogs who have been spayed. This type of infection is called a stump pyometra. It can develop when residual uterine or ovarian tissue is left after a spay or as a result of a reaction to the internal suture used during the spay surgery. This type of pyometra can happen as soon as days after the procedure is complete, or even years later. While stump pyometra is relatively uncommon, the signs of this condition are similar to a true pyometra.

Symptoms of Pyometra

Signs of canine pyometra can be difficult to spot, depending on which type of the infection a dog is suffering from. It's important to seek emergency veterinary care if you recognize the following symptoms.

  • Vaginal discharge - Discharge from the vulva is only be seen in cases of open pyometra. It may be a green/yellow color, appear white, or look blood-tinged.
  • Foul odor - Many people complain of a fishy odor or other unpleasant smell coming from their dog before they are diagnosed with pyometra.
  • Distended abdomen - You may notice your dog's belly is rounder or more bloated as a result of pus build up from the infection, and it can cause tenderness in the area.
  • Lethargy - A dog with a pyometra will appear to be sluggish and sleepy as all their energy becomes directed at fighting the infection. Some dogs may become so weak that they collapse.
  • Loss of appetite - This is a common sign of many illnesses, and a case of canine pyometra is no exception. An animal that doesn't feel well for any reason may not feel like eating, so always take this as an early warning sign that needs to be paid the proper attention.
  • Panting - Affected dogs may pant as a result of nausea or pain.
  • Fever - As with any infection, fever develops as the immune system attempts to fight off the invaders.
  • Increased thirst and urination - You may observe excessive thirst in an infected dog as a response to the fever, but their body will also increase urine output as it tries to flush out the infection.
  • Vomiting - This can also be observed with a case of pyometra as well as many other illnesses.

Reaching a Diagnosis

Although you may begin to suspect a uterine infection has developed if you notice one or more of the symptoms listed above, you'll still need your vet's help to make a proper diagnosis and administer life-saving treatment. In addition to looking for the symptoms, your veterinarian will perform a full physical exam.

Part of this examination involves gently palpating the abdomen to feel for an accumulation of fluid. Generally, an ultrasound and/or X-ray is needed to reach a diagnosis. Blood tests are also important to identify any organ damage or sepsis, and these should be performed before your dog goes under anesthesia for treatment.

Treatment Options

Treatment is necessary for dogs with pyometra. Otherwise, if they do not receive the necessary care, they will not survive. Surgery to remove the infected uterus and effectively spay the dog is the preferred method of treatment. However, dogs who are very ill, in shock, or septic may need to be stabilized before it is safe for them to go under anesthesia. Post-surgical monitoring is often necessary.

Depending on the severity of the infection, it's possible medical management may be an effective treatment option. Medical treatment for pyometra involves hospitalizing the pet and administering medication to promote contraction of the uterus in order to expel the pus. This is generally only pursued in breeding dogs with open pyometra.

Prevent Pyometra in Female Dogs

You can help prevent pyometra by having your dog spayed at the appropriate age. However, early detection can help a dog survive pyometra, as they will die without proper treatment. If you have an unspayed female, you must remain vigilant after each heat cycle ends to monitor for signs of this life-threatening infection. Prompt action will give your beloved pet the best chance at a positive outcome.

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What Is Pyometra in Dogs? Signs, Symptoms and Treatment