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Canine Monocytic Ehrlichiosis (Bacterial Infectious Disease Ehrlichiosis) in Dogs

Occurrence: common
Location of illness: General/Whole body

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

CanineCanine refers to anything related to dogs. The term is used to describe characteristics, diseases, or specific aspects that specifically affect dogs. Monocytic Ehrlichiosis is a tick-borne infectiousInfectious describes the ability of a pathogen to be transmitted from one individual to another and trigger an infection. It also refers to diseases caused by such pathogens. disease in dogs caused by the bacterium Ehrlichia canis. It leads to 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 white blood cells and can cause a variety of clinical symptoms.

The most important facts at a glance

Canine Monocytic Ehrlichiosis 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. in dogs 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. of the genus Ehrlichia. 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. are mainly transmitted through the bite of the brown dog tick. 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. affects the white blood cells and can weaken the dog’s 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., making it more susceptible to further infections. The disease progresses in three phases: acuteAcute refers to a condition that occurs suddenly and is usually of short duration. In a medical context, it describes symptoms or illnesses that can quickly become serious and require immediate attention., subclinicalSubclinical refers to a condition or disease that does not yet cause any recognizable symptoms. Subclinical diseases can only be diagnosed by specific tests or examinations., and 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.. In the acuteAcute refers to a condition that occurs suddenly and is usually of short duration. In a medical context, it describes symptoms or illnesses that can quickly become serious and require immediate attention. phase, dogs often show nonspecific symptoms such as fever or loss of appetite. In the 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. phase, more serious symptoms such as anemia or organ damage can occur.

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 based on clinical symptoms and special blood tests that can detect anemia or a low platelet count. Serological tests and PCR tests help to confirm 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.. Treatment is usually with antibiotics, especially doxycycline, for at least four weeks. In severe cases, supportiveSupportive refers to supportive treatments that aim to alleviate symptoms and improve quality of life without directly treating the underlying cause of the disease. 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. 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 treatment are crucial to control the disease and avoid complications.

For preventionPrevention includes measures taken to prevent diseases or injuries. In veterinary medicine, this includes vaccinations, parasite control, and health monitoring., tick control is crucial. Regular use of tick repellents and examining the dog for ticks can reduce 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.. Despite treatment, some dogs may remain carriers of the 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. and are therefore prone to relapses. A vaccineA vaccine is a substance that stimulates the immune system to develop immunity against specific pathogens without causing the disease itself. Vaccines may contain weakened or inactivated pathogens, toxoids, or recombinant antigens. against Ehrlichia canis does not currently exist, so tick control remains the most important preventive measure.

Causes

Ehrlichiosis 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 organisms of the genus Ehrlichia. 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. are obligate intracellular pathogens that preferentially live in monocytes and macrophages, which can lead to a systemic disease. The primaryPrimary refers to the first or original cause of a disease or condition, as opposed to secondary causes or symptoms that develop from it. mode of transmission of this disease is through the bite of infected ticks, especially the brown dog tick (Rhipicephalus sanguineus).

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. begins when an infected tick feeds on a dog and transmits the 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. into the dog’s bloodstream. The 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. then infect the white blood cells and multiply within these cells. This 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. can lead to suppression of 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., making the dog susceptible to secondary infections.

The disease occurs in different phases: acuteAcute refers to a condition that occurs suddenly and is usually of short duration. In a medical context, it describes symptoms or illnesses that can quickly become serious and require immediate attention., subclinicalSubclinical refers to a condition or disease that does not yet cause any recognizable symptoms. Subclinical diseases can only be diagnosed by specific tests or examinations., and 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.. In the acuteAcute refers to a condition that occurs suddenly and is usually of short duration. In a medical context, it describes symptoms or illnesses that can quickly become serious and require immediate attention. phase, which can occur weeks to months after 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 dog often shows nonspecific symptoms. In the subclinicalSubclinical refers to a condition or disease that does not yet cause any recognizable symptoms. Subclinical diseases can only be diagnosed by specific tests or examinations. phase, the dog may not show any symptoms, while the 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. phase causes more severe health problems, such as anemia, tendency to bleed, and organ damage.

Symptoms

Very common symptoms:

Common symptoms:

Rare symptoms:

The symptoms of CanineCanine refers to anything related to dogs. The term is used to describe characteristics, diseases, or specific aspects that specifically affect dogs. Monocytic Ehrlichiosis can vary greatly and depend on the stage of the disease. In the acuteAcute refers to a condition that occurs suddenly and is usually of short duration. In a medical context, it describes symptoms or illnesses that can quickly become serious and require immediate attention. phase, dogs may show fever, loss of appetite, lethargy, and weight loss. There may also be lymph node swelling and an enlarged spleen.

In the subclinicalSubclinical refers to a condition or disease that does not yet cause any recognizable symptoms. Subclinical diseases can only be diagnosed by specific tests or examinations. phase, the dog may not show any obvious symptoms, although 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. persists in the body. This makes 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. difficult in this phase, as the dog may appear outwardly healthy.

In the 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. phase of the disease, more serious symptoms can occur. These include anemia, bleeding, which can manifest as nosebleeds or bruises, as well as joint pain and neurological symptoms. The 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. phase can also lead to multipleMultiple means manifold or repeated and is used to describe conditions or events that occur in multiple instances or at different locations. In veterinary medicine, this may indicate multiple lesions, tumors, or other pathological changes. organ failure, especially of the kidneys.

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 CanineCanine refers to anything related to dogs. The term is used to describe characteristics, diseases, or specific aspects that specifically affect dogs. Monocytic Ehrlichiosis is based on a combination of clinical symptoms, the dog’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., and specific diagnostic tests. Blood tests are crucial to detect abnormalities such as anemia, thrombocytopeniaThrombocytopenia is a condition in which the number of platelets in the blood is lower than normal, increasing the risk of mild to severe Bleeding. (low platelet count), and elevated liver enzyme levels.

Serological tests such as the indirect immunofluorescence assay (IFA) can be used to identify antibodies against Ehrlichia canis in the dog’s blood. These tests indicate whether the dog has come into contact with the 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. and has reacted to it.

Another diagnostic approach is the PCR test (polymerase chain reaction), which directly detects the presence of Ehrlichia DNADNA (deoxyribonucleic acid) is the molecule that carries the genetic instructions for the development, function, and reproduction of all known living organisms and many viruses. It is located in the cells of an organism and contains the information for heredity. in the dog’s blood. This test is particularly useful in the early phase 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., when antibodyAn antibody is a protein produced by the immune system to recognize and bind specific antigens. By binding to the antigen, antibodies can help destroy or neutralize it. titers may not yet be detectable.

Therapy

The treatment of Canine Monocytic Ehrlichiosis is usually done with antibiotics. Doxycycline is the most commonly used antibiotic and is administered over a period of at least 4 weeks. Early treatment can quickly relieve symptoms and control 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 severe cases, especially in the 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. phase, supportiveSupportive refers to supportive treatments that aim to alleviate symptoms and improve quality of life without directly treating the underlying cause of the disease. 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 required. This may include the administration of fluids for hydration, blood transfusions for severe anemia, and the treatment of secondary infections.

It is important to continue treatment consistently and have the dog regularly monitored by a veterinarian to ensure that the infection is completely eliminated and that there are no relapses.

Prognosis and follow-up care

The prognosis for dogs with Canine Monocytic Ehrlichiosis depends on the phase of the disease and the speed of treatment. Dogs treated in the acuteAcute refers to a condition that occurs suddenly and is usually of short duration. In a medical context, it describes symptoms or illnesses that can quickly become serious and require immediate attention. phase usually have a good 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. and recover completely.

In the chronic phase, 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 more guarded, as irreversible damage to organs can occur. 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 treatment are crucial to minimize the risk of long-term complications.

Some dogs may remain carriers of the 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. despite treatment and are prone to relapses, especially if 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. is weakened.

Prevention

The preventionPrevention includes measures taken to prevent diseases or injuries. In veterinary medicine, this includes vaccinations, parasite control, and health monitoring. of CanineCanine refers to anything related to dogs. The term is used to describe characteristics, diseases, or specific aspects that specifically affect dogs. Monocytic Ehrlichiosis focuses primarily on tick control. Regular use of tick repellents and controlling the dog’s environment for tick infestation are important measures to reduce the risk of infection.

It is also advisable to check dogs regularly for ticks, especially after stays in areas where ticks are common. Ticks should be removed as soon as possible to prevent the transmission of Ehrlichia 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..

Good general health care and regular veterinary check-ups can help monitor the dog’s health and respond early to possible infections. Currently, there is no vaccineA vaccine is a substance that stimulates the immune system to develop immunity against specific pathogens without causing the disease itself. Vaccines may contain weakened or inactivated pathogens, toxoids, or recombinant antigens. against Ehrlichia canis, so tick control remains the most important preventive measure.