Female dog at veterinarian's office.

Pyometra in Dogs

Pyometra is a term that describes a pus-filled, infected uterus. It is a life threatening condition that requires emergency stabilization and surgery for treatment. Since pyometra is an infection of the uterus, all unspayed dogs are susceptible.

There are multiple factors that can lead to the development of a uterine infection. Progesterone is a normal hormone that can promote endometrial growth and increase secretions, while decreasing motility in the uterus. Progesterone can also inhibit WBC activity, which can prevent the ability to fight off bacterial infections in the uterus. In addition to progesterone, intact female dogs can have cystic endometrial hyperplasia, which causes further accumulation of uterine secretions and can make an environment that is favorable for bacterial growth. The most common bacteria associated with this infection is Escherichia coli.

Pyometra usually occurs after a heat cycle in which a dog did not become pregnant. The bacteria stems from a urinary tract infection or normal vaginal flora that causes uterine contamination. Typically, pyometra develops around eight weeks following the heat cycle. It should not be confused with metritis, which is a uterine infection that develops following the birth of puppies.

Pyometra can be defined as open (draining pus out of the vagina through an open cervix) or closed (pus is trapped in the uterus due to a closed cervix). Closed pyometras are more dangerous, since the infection is trapped in the dog’s body.

The infection is not only life threatening on its own, but it can also cause kidney failure through bacterial toxins. If treated quickly with surgery and antibiotics, approximately 90% of dogs affected with pyometra will survive.

Clinical Signs of Pyometra

Signs of a pyometra may be vague and mimic other diseases.

The most common clinical signs are:

Diagnosis of Pyometra in Dogs

A complete medical history is important for diagnosis of a pyometra. Your veterinarian will ask specific questions about your pet’s appetite, activity level, and attitude. Animals with pyometra are often depressed and lethargic. They may vomit or have diarrhea and often show no interest in food. In order to diagnose pyometra, your veterinarian will ask questions to develop a complete history of the course of the disease.

These questions may include:

A physical exam performed by your veterinarian is important in the diagnostic process. This exam will include palpation of your pet’s abdomen for an enlarged uterus and examination of your pet’s vagina for discharge, tumors, or other abnormalities. Your veterinarian will also take your dog’s temperature to check for a fever.

Further diagnostics that are often needed to diagnose a pyometra include:

Treatment of Pyometra in Dogs

The ideal treatment for pyometra is an ovariohysterectomy (spay). Before surgery is performed, some patients may require emergency stabilization in the form of intravenous fluids and antibiotics, especially if septic shock or kidney failure have developed. Surgery is recommended to rid the body of the infected uterus and prevent recurrence.

There are non-surgical medical options, but they are not recommended as the first line of treatment. If the pyometra is open, allowing for uterine drainage, a course of antibiotics can be attempted. If the cervix is closed and drainage is not possible, antibiotic therapy will not be enough. Additional therapy with hormonal treatment has been used, especially in breeding females where surgery is not an option. Prostaglandin F2ɑ (PF2ɑ) is not approved for treatment of pyometras in the US, and medical therapy alone is not recommended. There is a high recurrence rate with hormonal treatment, and there is a two-day delay in its effectiveness, which could risk the patient’s life. 70% of dogs with open pyometras that are treated medically will have a recurrence within 2 years.

Spaying an animal that has pyometra remains the best standard of care. This therapeutic course will prevent recurrence of a pyometra, but also prevents them from having litters in the future.

Pyometras can be fatal if appropriate medical care is not provided.

Follow-up Care for Dogs with Pyometra

Optimal treatment for your dog requires a combination of home and professional veterinary care. Follow-up can be critical, especially if your dog does not rapidly improve.
Administer all prescribed medications as directed. Alert your veterinarian if you are experiencing problems treating your dog.

Be familiar with your pet’s appetite, attitude, and activity level. It can be very helpful if you notice subtle changes in your pet’s behavior, eating, drinking, or urination habits. The more you are aware of what is “normal” for your pet, the quicker you will be able to pick up on something going wrong. As with most diseases, early detection and intervention is best.

Be familiar with your dog’s body. If you notice any vaginal discharge or other signs associated with pyometra, contact your veterinarian.


The only way to prevent pyometra is to have your dog spayed. Discuss with your veterinarian when it is ideal to spay your dog. It is much safer and less expensive to have your dog spayed when they are young and healthy, instead of waiting for a medical crisis to necessitate anesthesia and abdominal surgery. Elective spay procedures are tolerated well by dogs and are typically same-day surgeries with discharge at the end of the day. Pyometra surgeries can be more difficult and may need multiple days of hospitalization with IV antibiotics to allow for recovery.