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Endometritis (Inflammation of the Uterine Lining) in Dogs

Occurrence: common
Location of illness: Abdomen/pelvis

Author: Dr. med. vet. Gisa Löwe | Last modified: 06.11.2025

Endometritis is an inflammatory condition of the uterine lining in dogs that can be triggered 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. or non-infectious causes. This inflammation can affect the dog’s 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. and, if left untreated, can lead to more serious health problems.

The most important facts at a glance

Endometritis in dogs is an inflammation of the uterine lining that can be caused by bacterial infections, hormonal imbalances, or mechanical injuries. The disease often occurs after birth when 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 still open and 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. can enter. Symptoms include apathyApathy refers to a state of indifference and reduced interest or lack of emotional involvement in activities or events that would normally arouse interest., loss of appetite, fever, and vaginalVaginal refers to anything related to the vagina, the muscular tube that connects the external genitalia in female mammals to the uterus. discharge. 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 examinations, 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., and possibly cytologycytology is the study of cells, their structure, function, and chemistry. In medicine, it often refers to examining cells under a microscope for diagnosis of diseases. or biopsyA biopsy is a medical procedure in which a small amount of tissue is removed from the body to be examined under a microscope for signs of disease. Biopsies can help diagnose cancer and other conditions.. Antibiotics are often used for treatment, and hormonal therapyTherapy refers to the treatment of diseases or disorders with the aim of alleviating symptoms, promoting healing, or improving quality of life. Therapies can be medicinal, surgical, or through other medical interventions. may be necessary for hormonal causes. In severe cases, 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. is required. Timely 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. significantly improves 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., while delayed treatment can lead to permanent 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. problems. PreventionPrevention includes measures taken to prevent diseases or injuries. In veterinary medicine, this includes vaccinations, parasite control, and health monitoring. measures include monitoring female dogs during birth and spaying. Research is investigating the role of the microbiome to develop new treatment strategies. The development of biomarkers for early and non-invasive 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., as well as the study of hormones and their influence on the disease, are also being intensively researched. In addition, alternative 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. therapies are being sought to combat 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.. The 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. to endometritis is also a focus to improve breeding programs and reduce the incidenceIncidence refers to the number of new cases of a disease or condition that occur within a specific time period in a specific population group. It provides information about the risk of contracting the disease. of the disease.

Causes

The uterine lining, also called the endometrium, is the inner layer 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 plays an essential role in reproduction. It provides the necessary environment for the implantation of an embryoAn embryo is the early stage of development of a multicellular organism after fertilization. In mammals, the term refers to the phase from fertilization to the formation of basic structures of the fetus. and supports its development. In the event of inflammation, such as endometritis, this function is significantly impaired.

Endometritis can develop in various ways. A common scenario is 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. caused by ascending microorganisms from the vagina 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.. Such infections often occur after birth (postpartum) or after a miscarriage, when 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 still open and 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. can enter more easily.

Non-infectious causes can be hormonal imbalances that lead to excessive proliferation of the uterine lining, making it more susceptible to inflammatory conditions. Mechanical irritation or injury to the lining, for example, due to improper obstetrics or manipulations, can also triggerA trigger is a stimulus that elicits a specific reaction or state. In veterinary medicine, this can refer to emotional responses, such as fear or aggression, or medical conditions, such as seizures in dogs and cats. endometritis.

Symptoms

Very common symptoms:

Common symptoms:

Rare symptoms:

The symptoms of endometritis in dogs can vary but are often non-specific. Common signs include an abnormal, often foul-smelling discharge from the vagina, which can occur in various colors from clear to 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.. This discharge is a direct result of the inflammatory conditions and 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 uterine lining.

In addition, affected dogs may show signs of discomfort, such as fever, loss of appetite, or lethargy. In some cases, 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. may also be palpable. In female dogs who do not become pregnant or repeatedly have miscarriages, endometritis could be the underlying cause.

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 endometritis usually begins with a thorough clinical examination of the dog, accompanied by a detailed 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. that includes information about reproductive status, cycle changes, or previous births. An important diagnostic clue may be the characteristic vaginalVaginal refers to anything related to the vagina, the muscular tube that connects the external genitalia in female mammals to the uterus. discharge.

To confirm 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., 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. are often used to detect changes in the structure 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., such as thickening or fluid accumulation. A cytologycytology is the study of cells, their structure, function, and chemistry. In medicine, it often refers to examining cells under a microscope for diagnosis of diseases. or culture 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 also be performed to identify the specific 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 are causing 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..

In some cases, an endoscopyEndoscopy is a diagnostic procedure that uses an endoscope (a thin, flexible tube with a light source and a camera at the end) to examine and visualize the inside of the body, often for diagnostic or therapeutic purposes. 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. or a tissue sample (biopsy) may be necessary to directly assess the condition of the uterine lining and rule out other conditions.

Therapy

The treatment of endometritis depends on the severity of the disease and the underlying cause. Antibiotic therapyTherapy refers to the treatment of diseases or disorders with the aim of alleviating symptoms, promoting healing, or improving quality of life. Therapies can be medicinal, surgical, or through other medical interventions. is often necessary to combat the 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.. The choice of antibiotic is ideally based on the results of bacterial culture and antibiotic sensitivity tests.

In cases where hormonal imbalances play a role, hormonal therapyTherapy refers to the treatment of diseases or disorders with the aim of alleviating symptoms, promoting healing, or improving quality of life. Therapies can be medicinal, surgical, or through other medical interventions. may be considered to restore the normal function of the uterine lining. In severe or chronicChronic refers to a condition or disease that is long-lasting or permanent. Chronic diseases often develop slowly and can lead to persistent or recurring health problems over time. cases, 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. (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.) may be necessary, especially if there is a risk of pyometra, a life-threatening 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..

In addition to these treatments, supporting the dog’s general health is important, including a balanced diet and possibly complementary therapies 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..

Prognosis and follow-up care

The prognosis for dogs with endometritis depends heavily on early 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 the effectiveness of treatment. With timely and appropriate treatment, 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 often good, and many dogs recover completely and can have normal reproductive cycles again.

In chronic cases or if the disease is not detected in time, 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. may be worse, as the uterine lining may be irreversibly damaged, leading to permanent 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. problems or other health complications.

Prevention

The preventionPrevention includes measures taken to prevent diseases or injuries. In veterinary medicine, this includes vaccinations, parasite control, and health monitoring. of endometritis in dogs involves several approaches. One of the most effective methods is careful monitoring and care of female dogs during and after birth to prevent infections. This includes a clean environment and, if necessary, veterinary assistance for complications during birth.

Spaying (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.) is another preventive measure, especially for dogs that are not used for breeding. It completely eliminates the possibility of uterine inflammation.

Regular veterinary examinations, including monitoring of reproductive health status, can also help detect early signs of endometritis and treat it in a timely manner.

Outlook on current research

Endometritis in dogs is an inflammatory condition that affects the uterine lining and can have various causes, including bacterial infections, hormonal disorders, or the presence of foreign bodies. Current research focuses particularly on the role of the uterine microbiome. Researchers are investigating how changes in the bacterial composition of the uterus can influence the development of endometritis. It is believed that an imbalanceImbalance refers to an imbalance or disruption of normal function or composition in the body, which can lead to health problems. in the microbiome can amplify the inflammatory response. This could lead to new therapeutic approaches in which the microbiome is used as a target for treatment strategies.

Another promising area of research is the investigation of biomarkers in blood or urine that could enable early 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 endometritis. Currently, diagnostic methods are often invasive and require 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. examinations or biopsies. By identifying specific biomarkers that are related to the inflammatory conditions, a non-invasive diagnostic method could be developed. 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 show that certain proteins in the blood of dogs with endometritis may be elevated, which provides a basis for further research.

In addition, the role of hormones, especially progesterone, in the pathogenesisPathogenesis describes the process of the origin and development of a disease, including the mechanisms that lead to the disease's symptoms and signs. of endometritis is being studied in more detail. Progesterone has an immunosuppressiveImmunosuppressive agents are medications or substances that specifically suppress the activity of the immune system. They are used in dogs and cats to treat autoimmune diseases, allergies, and to prevent rejection reactions after transplants. effect and can increase the risk of infections. Researchers are working to understand how hormonal changes 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 related to the development and 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 endometritis. These findings could lead to better preventionPrevention includes measures taken to prevent diseases or injuries. In veterinary medicine, this includes vaccinations, parasite control, and health monitoring. strategies in the long term, especially in female dogs used for breeding purposes.

Another area of research is the development of new antibiotics or alternative 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. therapies, as increasing 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 global problem. Some scientists are investigating the use of phage therapies, in which bacteriophages are specifically used against the pathogenic 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 can cause endometritis. This method could be a promising alternative to conventional antibiotics and help to circumvent the 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. problem.

Finally, there are also research efforts focusing on the 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. to endometritis. By identifying genetic markers that are associated with a higher risk for this disease, breeders could be able to develop targeted breeding programs to reduce the incidenceIncidence refers to the number of new cases of a disease or condition that occur within a specific time period in a specific population group. It provides information about the risk of contracting the disease. of the disease in certain breeds. However, this requires comprehensive genetic studies and close collaboration between scientists and breeders.

Frequently asked questions (FAQs)

What is endometritis in dogs? Endometritis is an inflammation of the uterine lining (endometrium) in dogs. This condition can be caused by bacterial infections, hormonal disorders, or the presence of foreign bodies 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..
What symptoms does a dog with endometritis show? The symptoms can vary but often include vaginal discharge, lethargy, decreased appetite, and fever. In some cases, the female dog may also show pain or have a swelling in 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. area.
How is endometritis diagnosed in dogs? 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 clinical examinations, 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., and sometimes a biopsyA biopsy is a medical procedure in which a small amount of tissue is removed from the body to be examined under a microscope for signs of disease. Biopsies can help diagnose cancer and other conditions. of the uterine lining. Blood tests can also be performed to check for inflammatory conditions markers.
Can endometritis be treated in dogs? Yes, endometritis can usually be treated with antibiotics. In more severe cases, 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. (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.) may be necessary, especially if pyometra has developed.
How can endometritis be prevented in dogs? Spaying is the most reliable method to prevent endometritis. For dogs that are not to be spayed, careful monitoring during the cycle is important, as is avoiding mating with infected partners.
What role do hormones play in endometritis? Hormones, especially progesterone, can affect 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 uterine lining and increase the risk of infections. 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., hormonal changes can increase susceptibility to endometritis.
Are certain dog breeds more susceptible to endometritis? Yes, some breeds show a higher 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. to hormonal and reproductive diseases, including endometritis. This may have genetic causes, which is why breeding programs should pay attention to this.
Can endometritis lead to other health problems? Yes, untreated endometritis can lead to serious complications, such as pyometra, 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. inflammation 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 can be life-threatening. Sepsis is also possible.
How common is endometritis in dogs? The exact frequency varies, but it is a relatively common disease in non-spayed female dogs, especially in middle to older age. Regular veterinary check-ups are important to detect early signs.
Are there new treatment methods for endometritis? Currently, research is being conducted on alternative treatment approaches such as phage therapyTherapy refers to the treatment of diseases or disorders with the aim of alleviating symptoms, promoting healing, or improving quality of life. Therapies can be medicinal, surgical, or through other medical interventions., which specifically targets pathogenic 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.. This method could offer a solution to the problem of 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..