Female pets who are not spayed are at an increased risk for several serious health conditions, including several cancer types. Because risk increases with each successive reproductive cycle, our Southern Arizona Veterinary Specialty & Emergency Center team recommends that all female pets not slated for breeding be spayed by their primary care veterinarian as a preventive measure. 

Pets who remain intact for breeding or other reasons, such as limited access to veterinary care or differing cultural beliefs, are also at risk for a uterine infection called pyometra. Pyometra can quickly threaten a female pet’s life and requires prompt emergency care. We answer frequently asked client questions about pyometra to help pet owners understand the seriousness of this condition.

Question: What is pyometra in pets?

Answer: Pyometra is an infection in a female pet’s uterus (i.e., womb). The name pyometra, translated from its Latin components, means “pus in the uterus.” In an infected pet, the normally small, Y-shaped uterus becomes filled and distended with bacteria and purulent debris, and the pet becomes systemically sick. A pyometra is an emergency, because the uterus can rupture or die and leak toxins and bacteria into the pet’s abdomen and bloodstream. Pets can pass away from pyometra without prompt treatment.

Q: How does pyometra develop in pets?

A: Pyometra develops because of the hormonal influences exerted on the uterus during a normal heat cycle. Estrogen and progesterone stimulate the uterine lining to thicken in preparation for pregnancy, but in pets who don’t get pregnant, the thickened lining can end up nourishing bacteria instead of eggs. Because of the conditions in the uterus, the infection can quickly proliferate and grow out of control beyond the immune system’s ability to handle.

Q: Which pets are at risk for pyometra?

A: Any intact (i.e., unspayed) female pet is at risk for pyometra, although the risk increases as pets get older and go through multiple heat cycles. Older pets tend to develop a thicker or cystic uterine lining, and their immune systems are less able to fight off bacterial infections. 

Q: How do I know if my pet has pyometra?

A: You should suspect your pet has pyometra if they are an intact female showing general illness signs, including fever, lethargy, poor appetite, vomiting, and drinking water excessively. The signs will usually develop over a few hours or days, although some forms can be present for longer. 

The severity of your pet’s illness may depend partly on whether the pyometra is “open” or “closed” (i.e., whether the pet’s cervix is open or closed). An open pyometra allows the infected uterine contents to drain out through the vagina, which you may notice on your pet’s skin or bedding. A closed pyometra cannot drain, and your pet will get sick more rapidly.

Your veterinary team can diagnose pyometra based on the pet’s history, a complete physical examination, and several diagnostic tests. Tests required may include:

Q: How do veterinarians treat pets with pyometra?

A: The ideal treatment is emergency surgery to remove the infected uterus and the ovaries, which produce hormones. If the ovaries are not removed, any remaining uterine tissue (i.e., the uterine stump) can become reinfected. Most pets must be medically stabilized prior to surgery and hospitalized for supportive care and intravenous antibiotics for several days afterward.

Q: Is pyometra surgery the same as spay surgery?

A: Although both surgeries remove the same organs, the pyometra surgery is significantly riskier and more complex than a traditional spay. Pets with a pyometra are typically unstable and at risk for anesthetic complications, and the surgeon must take extreme care to avoid rupturing the fragile uterine tissue and spreading the infection to other abdominal organs. Spay surgery is far safer, more routine, and much less expensive than pyometra surgery.

Q: Will my pet recover from pyometra?

A: Most pets who are treated surgically and receive intensive care in the hospital can recover. Some may succumb to their infection if postoperative complications develop or treatment is started too late. Spaying your pet at a young age, or as soon as they are finished with their breeding career, and seeking veterinary care right away if your female pet is sick best ensures pyometra does not develop.

Intact female pets are at risk for several health conditions, including pyometra. Talk to your primary care veterinarian about spaying your young or adult pet and the ideal timing, depending on their species and breed. Contact the Southern Arizona Veterinary Specialty & Emergency Center for urgent evaluation and treatment if your female pet shows pyometra signs or for any other emergency care needs.