Uh-oh, Pyo! Pyometra in Female Pets

Pyometra is a serious and life-threatening condition that affects intact (i.e., unspayed) female pets when their uterus fills with harmful bacteria, sometimes causing fatal toxicity. Sadly, many pet owners don’t realize that unspayed pets are commonly at high risk, and they may miss early warning signs.

Learn everything you need to know about pyometra in this guide from Ambleside Animal Hospital.

What is pyometra in pets?

If you divide the word into its components, pyometra literally means pus- (i.e., pyo-) filled uterus (i.e., -metra). Pyometra typically occurs after the unspayed pet’s estrus (i.e., heat) cycle has ended. Although the cause isn’t fully understood, experts believe that the initiating bacteria (e.g., E.coli spp) enter the uterus during the heat cycle through the urinary tract or vagina.

Pyometra results when the uterus—a large, tubular Y-shaped organ—does not return to normal after estrus and becomes the perfect environment for rapid bacterial growth. In some cases, pet owners mistake their pet’s increasingly swollen abdomen as pregnancy.

Pyometra types in pets

Pyometra in pets can take several forms, including:

  • Open pyometra — During an open pyometra, the cervix (i.e., the tube that connects the uterus to the outside world) remains open, allowing the fluid to drain.
  • Closed pyometra — Closed pyometra puts pets in incredible danger, because infected contents are trapped by the closed cervix. Untreated closed pyometra can rupture, and bacteria spill into the abdominal cavity. Because closed pyometra causes no discharge, it can be more challenging to identify until the pet is in critical condition.
  • Stump pyometra — Pyometra can occur, but rarely, if the uterine stump (i.e., base) isn’t fully removed during the spay surgery.

Although pyometra may seem like an isolated issue, an infection of this magnitude has powerful systemic effects throughout the body.

Pyometra risk factors for dogs and cats

Although any intact (i.e., unspayed) female dog or cat can develop a pyometra, risk can be increased by certain factors, including:

  • Age — Age-related uterine tissue changes can raise infection risk. Older dogs also have weaker immune systems and are less able to fight off infection.
  • Incomplete spay — Retained uterine tissue can lead to stump pyometra.
  • Previous pyometra — Pyometra is likely to reoccur.

Pyometra signs in pets

Understanding common pyometra signs can help you recognize this life-threatening emergency and take quick action. Signs generally appear around four to eight weeks after estrus ends and may include:

  • Loss of appetite
  • Lethargy
  • Depression
  • Pale gums
  • Increased thirst and urination
  • Swollen abdomen
  • Vomiting and diarrhea
  • Vaginal discharge, which may be milky or bloody, occurs only during open pyometra

Because some pets show only vague, nonspecific signs, the American College of Veterinary Surgeons advises veterinarians to consider pyometra in any sick, unspayed pet. If your pet has pyometra signs or simply does not seem normal one or two months after their heat cycle, seek immediate veterinary care at Ambleside Animal Hospital.

Emergency! Pyometra diagnosis for pets

If your pet’s veterinarian suspects pyometra they will perform a complete physical examination to look for clinical signs and rule out other causes. Additional diagnostic testing is necessary to confirm pyometra and determine the treatment plan. Recommended testing includes:

  • Blood work
  • Urinalysis
  • X-rays or ultrasound imaging

Pyometra treatment for pets

Emergency spay surgery, which is the recommended pyometra treatment, is curative. During a pyometra spay, the veterinarian carefully ties off and removes the ovaries and the entire infected uterine body, which can weigh several pounds, and effectively eliminates the infection and its source. However, because pyometra makes pets extremely sick, this otherwise routine procedure is considered high-risk, and your pet must be monitored and hospitalized post-surgery to ensure a safe recovery.

If the pet is part of a breeding program and in stable condition, uterine-sparing therapy, which is a non-surgical option that involves administering injectable prostaglandins to relax and empty the uterus, may be attempted. Owners will be advised to breed their pet at the next heat cycle, watch for recurrence, and have their pet spayed after completing their intended breedings.

Sadly, if the pet’s uterus ruptures (i.e., closed pyometra) prior to receiving veterinary attention, the prognosis is generally poor.

Pyometra prevention in pets

Spay surgery is the only way to completely prevent pyometra in dogs and cats. Because pyometra risk and the likelihood for other reproductive problems increases with age, the Ambleside Animal Hospital veterinarians recommend spaying your pet prior to their first heat cycle or after skeletal maturity (i.e., 14 to 16 months of age) for large- and giant-breed dogs.

If you choose to keep your female pet intact, you should track and monitor their estrus cycles and watch for pyometra signs.

Pyometra is a life-threatening emergency that requires immediate veterinary attention. If your female dog or cat is exhibiting pyometra signs, contact Ambleside Animal Hospital.