Home » Diseases » In cats » Pyometra (Uterine Infection)

Pyometra (Uterine Infection) in cats

Occurrence: rarer
Location of illness: Abdomen/pelvis

Author: Dr. med. vet. Gisa Löwe | Last modified: 03.12.2025

Pyometra, also known as uterusThe uterus, also known as the womb, is a female reproductive organ in which the fetus grows and develops during pregnancy. It consists of muscle tissue and is lined with a mucous membrane. suppuration, is a serious and potentially life-threatening condition in cats, characterized by an infectionAn infection is the colonization and multiplication of pathogens such as bacteria, viruses, fungi, or parasites in an organism, which often, but not always, leads to a disease. of the uterusThe uterus, also known as the womb, is a female reproductive organ in which the fetus grows and develops during pregnancy. It consists of muscle tissue and is lined with a mucous membrane. that often leads to an accumulation of pus in the uterusThe uterus, also known as the womb, is a female reproductive organ in which the fetus grows and develops during pregnancy. It consists of muscle tissue and is lined with a mucous membrane..

The most important facts at a glance

Pyometra is a serious condition in unneutered female cats caused by a bacterial infectionAn infection is the colonization and multiplication of pathogens such as bacteria, viruses, fungi, or parasites in an organism, which often, but not always, leads to a disease. of the uterusThe uterus, also known as the womb, is a female reproductive organ in which the fetus grows and develops during pregnancy. It consists of muscle tissue and is lined with a mucous membrane.. It often occurs after a heat cycle when progesterone levels are elevated, making the uterine lining more susceptible to infectionAn infection is the colonization and multiplication of pathogens such as bacteria, viruses, fungi, or parasites in an organism, which often, but not always, leads to a disease.. BacteriaBacteria are microscopic, single-celled organisms that exist in almost every environment on Earth. Some types of bacteria are beneficial or even essential to life, while others can cause disease. such as Escherichia coli can enter the uterusThe uterus, also known as the womb, is a female reproductive organ in which the fetus grows and develops during pregnancy. It consists of muscle tissue and is lined with a mucous membrane. through the cervixThe cervix is the lower part of the uterus that opens into the vagina. It plays an important role in reproduction and menstruation., especially when it is open. Cystic endometrial hyperplasiaHyperplasia refers to an increase in the number of cells in a tissue or organ, leading to enlargement. This can be a normal reaction or a sign of a disease. can further increase the risk. Symptoms include purulentPurulent refers to pus or the production of pus, which may indicate a bacterial infection. Purulent inflammatory conditions are often painful and may have significant swelling and redness. discharge, excessive grooming, loss of appetite, increased thirst and urination, weakness, vomiting, and fever. The diagnosisA diagnosis is the identification of a disease or condition by its symptoms and/or results from diagnostic tests. It is the first step in the management and treatment of patients. is made through clinical symptoms, blood tests, and imaging procedures such as ultrasoundUltrasound refers to sound waves that are above the hearing threshold of the human ear. In medicine, ultrasound is used for diagnostic imaging procedures to visualize internal organs, tissues, and blood flow.. The standard treatment is surgical removal of the uterusThe uterus, also known as the womb, is a female reproductive organ in which the fetus grows and develops during pregnancy. It consists of muscle tissue and is lined with a mucous membrane. and ovaries, known as ovariohysterectomyAn ovariohysterectomy is a surgical procedure in which the ovaries and uterus are removed. It is a standard procedure for castration / neutering female animals, especially dogs and cats. An ovariohysterectomy not only prevents unwanted reproduction, but also prevents certain diseases of the female reproductive organs.. In some cases, medical treatment of the uterusThe uterus, also known as the womb, is a female reproductive organ in which the fetus grows and develops during pregnancy. It consists of muscle tissue and is lined with a mucous membrane. is attempted, but with significant risks. The prognosisThe prognosis is the prediction of the likely course and outcome of a disease based on the general state of health, the nature of the disease, and the response to treatment. It can provide information on how a disease is expected to develop. is good if the condition is recognized and treated in time. Castration / neuteringCastration / neutering is the process of removing the gonads (ovaries in females, testicles in males), which prevents reproduction and the production of certain sex hormones. This can be done for medical or other reasons. is recommended for preventionPrevention includes measures taken to prevent diseases or injuries. In veterinary medicine, this includes vaccinations, parasite control, and health monitoring. to completely eliminate the risk. Researchers are working to improve diagnostics and treatment, including the development of vaccines and the investigation of genetic factors to better understand and minimize the risk.

Causes

Pyometra occurs most often in non-neutered female cats, especially in middle to older age. The condition is hormone-dependent and typically arises after a heat cycle when progesterone levels are elevated in the cat’s body. Progesterone prepares the uterine lining to support a possible pregnancy but can also make the lining more susceptible to infectionAn infection is the colonization and multiplication of pathogens such as bacteria, viruses, fungi, or parasites in an organism, which often, but not always, leads to a disease..

An important factor in the development of pyometra is the presence of bacteriaBacteria are microscopic, single-celled organisms that exist in almost every environment on Earth. Some types of bacteria are beneficial or even essential to life, while others can cause disease. in the uterusThe uterus, also known as the womb, is a female reproductive organ in which the fetus grows and develops during pregnancy. It consists of muscle tissue and is lined with a mucous membrane.. These bacteriaBacteria are microscopic, single-celled organisms that exist in almost every environment on Earth. Some types of bacteria are beneficial or even essential to life, while others can cause disease., often Escherichia coli, can ascend into the uterusThe uterus, also known as the womb, is a female reproductive organ in which the fetus grows and develops during pregnancy. It consists of muscle tissue and is lined with a mucous membrane. via the cervixThe cervix is the lower part of the uterus that opens into the vagina. It plays an important role in reproduction and menstruation., especially when it is open during the estrous cycleThe estrous cycle is the cycle of sexual reproduction in female mammals, which is divided into different phases, including estrus (heat). The cycle includes changes in behavior as well as physiological changes.. Progesterone can also weaken the immune responseAn immune response is the immune system's reaction to foreign substances (antigens), such as microorganisms or proteins. It involves a series of processes aimed at recognizing, fighting, and eliminating these antigens. of the uterusThe uterus, also known as the womb, is a female reproductive organ in which the fetus grows and develops during pregnancy. It consists of muscle tissue and is lined with a mucous membrane., which increases the likelihood of an infectionAn infection is the colonization and multiplication of pathogens such as bacteria, viruses, fungi, or parasites in an organism, which often, but not always, leads to a disease. developing.

Another crucial point is the structure of the uterine lining, which can change after several cycles. These changes, known as cystic endometrial hyperplasiaHyperplasia refers to an increase in the number of cells in a tissue or organ, leading to enlargement. This can be a normal reaction or a sign of a disease., create an environment that favors the growth of bacteriaBacteria are microscopic, single-celled organisms that exist in almost every environment on Earth. Some types of bacteria are beneficial or even essential to life, while others can cause disease., thus increasing the risk of pyometra.

Symptoms

Very common symptoms:

Common symptoms:

The symptoms of pyometra can vary depending on the stage of the disease and whether the cervixThe cervix is the lower part of the uterus that opens into the vagina. It plays an important role in reproduction and menstruation. is open or closed. In open pyometra, where the cervixThe cervix is the lower part of the uterus that opens into the vagina. It plays an important role in reproduction and menstruation. remains open, a purulentPurulent refers to pus or the production of pus, which may indicate a bacterial infection. Purulent inflammatory conditions are often painful and may have significant swelling and redness., often foul-smelling discharge from the vagina may be observed. In closed pyometra, the pus remains trapped in the uterusThe uterus, also known as the womb, is a female reproductive organ in which the fetus grows and develops during pregnancy. It consists of muscle tissue and is lined with a mucous membrane., which can lead to a rapid deterioration of health.

General symptoms include lethargy, loss of appetite, increased thirst (polydipsiaPolydipsia refers to an increased feeling of thirst and increased fluid intake. It can be a symptom of various diseases, including diabetes mellitus and kidney disease.), frequent urination (polyuriaPolyuria refers to a significantly increased urine output. It can be a symptom of various diseases, including diabetes mellitus, kidney disease, and hormonal disorders.), and Vomiting. Fever may also occur, but is not always present. In severe cases, a bloated abdomenThe abdomen, also known as the abdominal cavity, is the part of the body located between the rib cage and the pelvis. It houses several important organs, including the stomach, liver, kidneys, intestines, and spleen. may occur, indicating an enlarged uterusThe uterus, also known as the womb, is a female reproductive organ in which the fetus grows and develops during pregnancy. It consists of muscle tissue and is lined with a mucous membrane. filled with pus. Without prompt treatment, pyometra can lead to shock and Death.

Diagnosis

The diagnosisA diagnosis is the identification of a disease or condition by its symptoms and/or results from diagnostic tests. It is the first step in the management and treatment of patients. of pyometra is based on a combination of clinical symptoms, a thorough physical examination, and diagnostic tests. An experienced veterinarian will consider the cat’s medical historyThe medical history is the systematic collection of a patient's medical history through questioning. It includes information about previous illnesses, treatments, allergies, and lifestyle habits., especially its estrous cycleThe estrous cycle is the cycle of sexual reproduction in female mammals, which is divided into different phases, including estrus (heat). The cycle includes changes in behavior as well as physiological changes.. A blood testA blood test is a laboratory procedure in which blood is drawn and analyzed to obtain information about the body's health. It can include various parameters such as blood sugar, blood count, liver and kidney values. may show elevated white blood cells and changes in the electrolyte balanceThe electrolyte balance refers to the balance of electrolytes in the body, which is essential for many physiological processes. Disturbances in the electrolyte balance can lead to serious health problems., indicating an infectionAn infection is the colonization and multiplication of pathogens such as bacteria, viruses, fungi, or parasites in an organism, which often, but not always, leads to a disease..

An ultrasoundUltrasound refers to sound waves that are above the hearing threshold of the human ear. In medicine, ultrasound is used for diagnostic imaging procedures to visualize internal organs, tissues, and blood flow. of the abdominalThe term "abdominal" refers to anything that concerns the belly or the abdomen. It is an adjectival expression used to describe the location, symptoms, or conditions that occur in the abdominal area. cavity is a valuable diagnostic tool to visualize the enlarged uterusThe uterus, also known as the womb, is a female reproductive organ in which the fetus grows and develops during pregnancy. It consists of muscle tissue and is lined with a mucous membrane. and to distinguish between an open and a closed pyometra. X-rayX-ray is an imaging technique that uses X-rays to create images of the inside of the body. It is often used to diagnose bone fractures, lung diseases, and other conditions. images can also be helpful, especially if a closed pyometra is suspected. In some cases, a sample of the vaginalVaginal refers to anything related to the vagina, the muscular tube that connects the external genitalia in female mammals to the uterus. discharge can be taken for a bacteriological examination.

Therapy

The standard treatment for pyometra is surgical removal of the uterusThe uterus, also known as the womb, is a female reproductive organ in which the fetus grows and develops during pregnancy. It consists of muscle tissue and is lined with a mucous membrane. and ovaries, known as ovariohysterectomyAn ovariohysterectomy is a surgical procedure in which the ovaries and uterus are removed. It is a standard procedure for castration / neutering female animals, especially dogs and cats. An ovariohysterectomy not only prevents unwanted reproduction, but also prevents certain diseases of the female reproductive organs.. This surgery is generally the safest and most effective treatment method, especially for closed pyometra. Before the surgery, the cat often receives intravenous fluids and antibiotics to stabilize its condition.

In certain cases, especially in breeding cats, an attempt can be made to treat the uterusThe uterus, also known as the womb, is a female reproductive organ in which the fetus grows and develops during pregnancy. It consists of muscle tissue and is lined with a mucous membrane. medically to preserve fertilityFertility refers to the ability to conceive and bear offspring. In women, it refers to the ability to initiate and carry a pregnancy; in men, it refers to the ability to produce fertile sperm.. This treatment involves administering prostaglandins, which open the cervix and promote uterine contractions to expel the pus. However, this method carries significant risks and is not always successful.

Prognosis and follow-up care

The prognosis for cats with pyometra that are treated surgically in a timely manner is generally good. After the removal of the infected uterusThe uterus, also known as the womb, is a female reproductive organ in which the fetus grows and develops during pregnancy. It consists of muscle tissue and is lined with a mucous membrane., most cats recover completely and return to their normal activity. PostoperativePostoperative refers to the time after a surgical operation. This phase includes recovery and the management of possible complications after the procedure. care is crucial to avoid complications and typically includes the administration of antibiotics and pain relievers.

Without treatment, pyometra can quickly lead to serious complications such as peritonitis, sepsis, and ultimately Death. In a closed pyometra, the cat’s condition often deteriorates rapidly, making a quick diagnosisA diagnosis is the identification of a disease or condition by its symptoms and/or results from diagnostic tests. It is the first step in the management and treatment of patients. and treatment essential.

Prevention

The most important measure for the preventionPrevention includes measures taken to prevent diseases or injuries. In veterinary medicine, this includes vaccinations, parasite control, and health monitoring. of pyometra in cats is castration / neuteringCastration / neutering is the process of removing the gonads (ovaries in females, testicles in males), which prevents reproduction and the production of certain sex hormones. This can be done for medical or other reasons.. By removing the uterusThe uterus, also known as the womb, is a female reproductive organ in which the fetus grows and develops during pregnancy. It consists of muscle tissue and is lined with a mucous membrane. and ovaries, the risk of this disease is completely eliminated. Castration / neuteringCastration / neutering is the process of removing the gonads (ovaries in females, testicles in males), which prevents reproduction and the production of certain sex hormones. This can be done for medical or other reasons. is generally recommended once the cat is old enough to safely undergo the procedure, often at around six months of age.

In addition to castration / neuteringCastration / neutering is the process of removing the gonads (ovaries in females, testicles in males), which prevents reproduction and the production of certain sex hormones. This can be done for medical or other reasons., it is important to monitor the cat’s general health and schedule regular veterinary visits. Attention should be paid to changes in behavior or health that may indicate hormonal problems. A balanced diet and appropriate weight control also contribute to general health care.

If the cat is not neutered, it should be regularly checked for signs of infection or other reproductive problems. Some veterinarians also recommend limiting contact with unneutered male cats to reduce hormonal stimulation and the risk of uterine infections.

These preventive measures can significantly reduce the risk of pyometra, contributing to a longer and healthier life for the cat. Early preventionPrevention includes measures taken to prevent diseases or injuries. In veterinary medicine, this includes vaccinations, parasite control, and health monitoring. is key to avoiding serious health problems.

Outlook on current research

Pyometra is a serious condition in cats caused by a bacterial infectionAn infection is the colonization and multiplication of pathogens such as bacteria, viruses, fungi, or parasites in an organism, which often, but not always, leads to a disease. of the uterus. Current research is focusing on improving diagnostic procedures. Researchers are investigating the use of imaging techniques, such as ultrasound technology, to improve the early detection of this disease. Through detailed imaging diagnostic methods, veterinarians can detect pyometra earlier, which could significantly improve treatment options.

Another area of research focuses on the genetic factors that may contribute to susceptibility to pyometra. Scientists are analyzing genetic markers to determine whether certain cats have a genetic predispositionA predisposition is an innate inclination or susceptibility of an organism to certain diseases or conditions. In dogs and cats, there may be a genetic predisposition to certain conditions such as hip dysplasia or certain heart diseases. for this disease. In the long term, these findings could lead to the development of preventive measures for susceptible cats to minimize the risk of disease.

In addition, intensive research is being conducted into the development of new therapeutic approaches. Antibiotic resistanceResistance refers to the ability of microorganisms to withstand the effects of antibiotics, antifungals, or other antimicrobial drugs. Resistance can also refer to the body's ability to be insensitive to diseases or toxins. is a growing problem, not only in human medicine but also in veterinary medicine. Researchers are investigating alternative treatment methods that can reduce the use of antibiotics. These include the use of probiotics to strengthen the immune systemThe immune system is the body's defense system against infectious agents such as bacteria, viruses, fungi, and parasites. It comprises a complex network of organs, cells, and molecules that work together to protect the body. and the exploration of new antimicrobialAn antimicrobial substance is an agent that serves to inhibit the growth of microorganisms such as bacteria, viruses, fungi, and protozoa, or to kill them. Antimicrobials are frequently used to treat infections. agents that specifically target the pathogens of pyometra.

Another exciting area of research is the development of vaccinations against the most common pathogens of pyometra. InitialInitial means beginning or at the start. In medicine, it can refer to the first symptoms of a disease or the first phase of a treatment process. studies in this area are promising and could, in the long term, lead to cats being effectively protected against this disease through vaccinationVaccination is the process of administering a vaccine to develop immunity against a specific infectious disease. It is one of the most effective methods of prevention of infectious diseases.. This would be a significant advance in the preventionPrevention includes measures taken to prevent diseases or injuries. In veterinary medicine, this includes vaccinations, parasite control, and health monitoring. of pyometra and would reduce the need for surgical interventions.

In addition, the role of hormones in the development of pyometra is being investigated. Researchers are analyzing how hormonal imbalances, particularly in connection with the estrous cycleThe estrous cycle is the cycle of sexual reproduction in female mammals, which is divided into different phases, including estrus (heat). The cycle includes changes in behavior as well as physiological changes., influence the development and course of the disease. These studies could lead to new hormonal treatments that reduce the risk of pyometra in non-neutered cats.

Frequently asked questions (FAQs)

What is Pyometra? Pyometra is a purulentPurulent refers to pus or the production of pus, which may indicate a bacterial infection. Purulent inflammatory conditions are often painful and may have significant swelling and redness. infectionAn infection is the colonization and multiplication of pathogens such as bacteria, viruses, fungi, or parasites in an organism, which often, but not always, leads to a disease. of the uterus in cats caused by bacteria. It often occurs in non-neutered, older cats and is a serious condition that requires prompt medical treatment.
What are the typical symptoms of pyometra? Typical symptoms include lethargy, loss of appetite, increased thirst, and increased urination. In some cases, there may be a purulentPurulent refers to pus or the production of pus, which may indicate a bacterial infection. Purulent inflammatory conditions are often painful and may have significant swelling and redness. discharge from the vagina. Vomiting and fever may also occur.
How is pyometra diagnosed? The diagnosisA diagnosis is the identification of a disease or condition by its symptoms and/or results from diagnostic tests. It is the first step in the management and treatment of patients. is usually made through a combination of clinical examination, blood tests, and imaging techniques such as ultrasoundUltrasound refers to sound waves that are above the hearing threshold of the human ear. In medicine, ultrasound is used for diagnostic imaging procedures to visualize internal organs, tissues, and blood flow. or X-rayX-ray is an imaging technique that uses X-rays to create images of the inside of the body. It is often used to diagnose bone fractures, lung diseases, and other conditions.. These methods help to assess the size and condition of the uterusThe uterus, also known as the womb, is a female reproductive organ in which the fetus grows and develops during pregnancy. It consists of muscle tissue and is lined with a mucous membrane..
What treatment options are available for pyometra? The most common treatment is surgical removal of the uterus and ovaries, known as ovariohysterectomy. In some cases, medical treatment may be considered, but surgical removal is usually the safest option.
Can pyometra be prevented? The most effective method of preventing pyometra is castration / neuteringCastration / neutering is the process of removing the gonads (ovaries in females, testicles in males), which prevents reproduction and the production of certain sex hormones. This can be done for medical or other reasons. of the cat. This removes the uterus and ovaries, eliminating the risk of infectionAn infection is the colonization and multiplication of pathogens such as bacteria, viruses, fungi, or parasites in an organism, which often, but not always, leads to a disease..
What is the risk of a cat developing pyometra? The risk is highest in older, non-neutered cats. Cats that frequently undergo hormonal changes, such as during the estrous cycleThe estrous cycle is the cycle of sexual reproduction in female mammals, which is divided into different phases, including estrus (heat). The cycle includes changes in behavior as well as physiological changes., are also at higher risk.
Is pyometra life-threatening? Yes, without timely treatment, pyometra can be life-threatening as it can lead to severe infections and complications such as sepsisSepsis is a life-threatening condition caused by the body's overwhelming response to an infection, which can lead to damage to its own tissues and organ failure.. A quick diagnosisA diagnosis is the identification of a disease or condition by its symptoms and/or results from diagnostic tests. It is the first step in the management and treatment of patients. and treatment are crucial for the cat’s survival.
How long does recovery take after pyometra surgery? Recovery after an ovariohysterectomyAn ovariohysterectomy is a surgical procedure in which the ovaries and uterus are removed. It is a standard procedure for castration / neutering female animals, especially dogs and cats. An ovariohysterectomy not only prevents unwanted reproduction, but also prevents certain diseases of the female reproductive organs. can vary depending on the cat’s health and the progressionProgression refers to the advancement or worsening of a disease over time. It describes an increase in the severity or extent of the disease symptoms. of the disease. The recovery phase usually lasts about two weeks, during which the cat needs rest and the surgical wound should be monitored.
Can antibiotics alone be used to treat pyometra? Antibiotics may be part of the treatment, but they are usually not sufficient to eliminate the infectionAn infection is the colonization and multiplication of pathogens such as bacteria, viruses, fungi, or parasites in an organism, which often, but not always, leads to a disease.. Surgical removal of the infected uterusThe uterus, also known as the womb, is a female reproductive organ in which the fetus grows and develops during pregnancy. It consists of muscle tissue and is lined with a mucous membrane. is usually necessary to treat the condition completely.
Can other animals in the household be infected by a cat with pyometra? No, pyometra is not contagiousContagious means infectious. Diseases that can easily be transmitted from one animal to another or from animals to humans are referred to as contagious. and cannot be transmitted to other animals. It is caused by bacteriaBacteria are microscopic, single-celled organisms that exist in almost every environment on Earth. Some types of bacteria are beneficial or even essential to life, while others can cause disease. that specifically infect the uterusThe uterus, also known as the womb, is a female reproductive organ in which the fetus grows and develops during pregnancy. It consists of muscle tissue and is lined with a mucous membrane. of the affected cat.

When to visit the vet?

Urgent see a veterinarian within 24 hours

If the condition worsens / symptoms persist, consult a veterinarian.