Pyometra is a life-threatening uterine infection that affects unspayed (i.e., intact or unaltered) female dogs and cats. But, appreciable pyometra signs can be vague or nonexistent, and the condition can progress unnoticed until widespread damage has occurred.

Understanding pyometra risks and costs can help you protect your female pet from this reproductive emergency

Pyometra in pets—the explanation

Pyometra is a bacterial infection that occurs when the previously empty Y-shaped uterus fills with bacteria-rich pus and fluid. The cause is not fully understood, but pyometra is influenced—if not triggered—by an intact pet’s natural hormone changes (i.e., progesterone and estrogen). During estrus (i.e., heat cycle), hormone fluctuations trigger the uterus to prepare for hosting a pregnancy. However, with each empty cycle (i.e., one that does not result in fertilization), the uterus lining thickens and opens the cervix—the door, so to speak—to ascending bacteria from the urogenital tract.

Once bacteria reach the uterus and the infection takes hold, pyometra is classified as open or closed, depending on whether the cervix remains open after the estrus phase has completed. An open cervix creates a channel to the outside, which allows infected uterine contents to empty, whereas a closed pyometra traps the bacteria inside the uterus, where they continuously multiply and release toxins to the bloodstream.

Pyometra in pets—risk factors and warning signs

Although all intact (i.e., unspayed) female pets can experience pyometra, the condition frequently affects older dogs and cats. It is important that all owners of female pets learn pyometra signs so they seek immediate veterinary care for their pet. Such signs will appear four to eight weeks after the pet’s last heat cycle and can include:

  • Lethargy
  • Excessive thirst and urination
  • Depression
  • Pale gums
  • Appetite loss
  • Bloody or milky vaginal discharge
  • Vomiting
  • Diarrhea
  • Abdominal swelling or pain

A pet with a closed pyometra may rapidly become ill as bacterial toxins in the bloodstream impair their organ function. However, despite the sometimes dramatic appearance of a closed pyometra, you should remember that some pets—especially cats—may show no signs, or only a mild vaginal discharge or abdominal swelling. 

Pyometra in pets—diagnosis

Pets with pyometra signs should receive immediate veterinary attention, because early intervention can minimize complications and increase the likelihood that your pet’s uterus can be spared, if necessary. If your veterinarian suspects a pyometra, they will first thoroughly examine your pet for visible signs such as abdominal swelling, discharge, and dull or lethargic mentation. They may recommend diagnostic testing (e.g., blood work, urinalysis, or vaginal cytology) to identify infection and inflammation that correspond with increased bacteria, and X-rays or ultrasound imaging to visualize the uterus’ condition (e.g., thickness, contents, or inflammation).

Pyometra in pets—treatment and management

Pets with suspected pyometra are often in critical condition when they are brought to Groves Veterinary Clinic, so our team first will work quickly to stabilize your pet prior to advancing to the next treatment stage.

An emergency spay (i.e., ovariohysterectomy) surgery, which involves removing the infected uterus and the ovaries, is the best pyometra treatment option. Spaying your pet not only eliminates the infection source, but also prevents any opportunity for pyometra recurrence, which is common. However, unlike a standard spay, pyometra surgery can be challenging for the veterinary team and endanger the pet, especially if they are already experiencing toxicity or shock. 

While spaying is strongly advised, a non-surgical, uterus-sparing alternative using a hormone injection to relax the pet’s uterus and stimulate contractions is available for breeding, working, or show pets with open pyometra. These effects assist the uterus in expelling its infected contents, although treatment can cause serious side effects (e.g., uterine rupture) and pets have a high recurrence risk.

Surgical and non-surgical treatment involves aggressive hospitalized care, including intravenous fluids, antibiotics, pain medication, and close monitoring for lingering infection or internal injury. 

Pyometra in pets—prognosis

According to the American College of Veterinary Surgeons, the survival rate for a pet with uncomplicated pyometra who undergoes a spay surgery is as high as 80% to 100%. However, pets with sepsis (i.e., blood infection), peritonitis (i.e., contaminated abdominal cavity caused by uterine rupture), or organ damage have a more guarded prognosis. 

Non-surgically managed pets with an open pyometra can recover successfully after prolonged hospitalization (i.e., up to one week), but they must be bred during the following heat cycle to prevent pyometra recurrence. The uterine damage makes successful conception and pregnancy more difficult following a pyometra.

Without treatment, pets with pyometra are quickly overwhelmed with widespread bacterial infection, followed by rapidly declining health, and death.

Pyometra in pets—prevention

You can likely tell that spaying is the best way to almost eliminate pyometra risk and mammary cancer risk in female pets. However, if you opt to keep your pet intact for showing, breeding, or health and development-related reasons, we strongly suggest tracking your pet’s estrus cycle to monitor their behavior and stay alert for potential pyometra signs. Breeders should spay their breeding females once they have finished their whelping or queening “careers.” Your Groves Veterinary Clinic veterinarian can help you determine the best age to spay your pet.

Pyometra is a life-threatening veterinary emergency, but is easily preventable. Groves Veterinary Clinic recommends spaying all female pets who are not used for show or breeding to avoid this potentially tragic, fast-moving infection. Contact our team to schedule your pet’s spay surgery.