Ehrlichiosis in Dogs (Canine Monocytic Ehrlichiosis, CME)
- Synonyms: Monocytic ehrlichiosis, canine ehrlichiosis, tropical canine pancytopenia
- Occurrence: common
- Location of disease: General/Whole body
When to visit the vet?
Urgent see a veterinarian within 24 hours
If the condition worsens / symptoms persist, consult a veterinarian.
Definition
Canine monocytic ehrlichiosis is a tick-borne infectious disease in dogs caused by the bacterium Ehrlichia canis. It leads to an infection of white blood cells and can trigger a wide range of clinical symptoms.
The most important facts at a glance
Canine monocytic ehrlichiosis is a bacterial infection in dogs caused by bacteria of the genus Ehrlichia. These bacteria are mainly transmitted through the bite of the brown dog tick. The infection affects white blood cells and can weaken the dog’s immune system, making it more susceptible to further infections. The disease progresses in three phases: acute, subclinical, and chronic. In the acute phase, dogs often show non-specific symptoms such as Fever or loss of appetite. In the chronic phase, more severe symptoms such as anemia or organ damage can occur.
Diagnosis is based on clinical symptoms and specific blood tests that can detect anemia or a low platelet count. Serology and PCR tests help confirm the infection. Treatment is usually with antibiotics, primarily doxycycline, for at least four weeks. In severe cases, supportive therapy may be required. Early diagnosis and treatment are crucial to control the disease and avoid complications.
For prevention, tick control is key. Regular use of tick preventatives and checking the dog for ticks can reduce the risk of infection. Despite treatment, some dogs may remain carriers of the bacteria and are therefore prone to relapses. A vaccine against Ehrlichia canis does not currently exist, so tick control remains the most important prevention measure.
Causes
Ehrlichiosis is a bacterial infection caused by organisms of the genus Ehrlichia. These bacteria are obligate intracellular pathogens that preferentially live in monocytes and macrophages, which can lead to a systemic disease. The primary mode of transmission is the bite of infected ticks, especially the brown dog tick (Rhipicephalus sanguineus).
The infection begins when an infected tick feeds on a dog and transmits the bacteria into the dog’s bloodstream. The bacteria then infect white blood cells and multiply within these cells. This infection can suppress the immune system and make the dog susceptible to secondary infections.
The disease occurs in different phases: acute, subclinical, and chronic. In the acute phase, which can occur weeks to months after infection, the dog often shows non-specific symptoms. In the subclinical phase, the dog may show no symptoms, while the chronic phase causes more serious health problems such as anemia, a tendency to bleed, and organ damage.
Symptoms
- Cough
- Petechiae (pinpoint hemorrhages)
- Pale Mucous Membranes
- Susceptibility to Infection
- General condition impaired
- Retinal hemorrhages
- Hyphema (Intraocular Hemorrhage)
- Conjunctivitis
- Fluid accumulation in the abdominal cavity (ascites)
- Leg edema
- Vomiting
- Diarrhea
- Bauchschmerzen
- Neurological Symptoms Such as Seizures, Disorientation, Behavioral Disorders
Symptoms of canine monocytic ehrlichiosis can vary widely and depend on the phase of the disease. In the acute phase, dogs may show Fever, loss of appetite, Lethargy, and Weight loss. Enlarged lymph nodes and an enlarged spleen can also occur.
In the subclinical phase, the dog may show no obvious symptoms even though the infection persists in the body. This makes diagnosis more difficult at this stage, as the dog may appear healthy on the outside.
In the chronic phase of the disease, more severe symptoms can occur. These include anemia, bleeding that may present as nosebleeds or bruising, as well as Joint pain and neurological symptoms. The chronic phase can also lead to multiple organ failure, especially of the kidneys.
Key symptoms: Fever spikes + Enlarged lymph nodes (lymphadenopathy) + Bleeding, Nose bleeds (epistaxis), pinpoint bleeding in the skin or mucous membranes (petechiae) ± Lameness after tick exposure.
Therapy
Treatment of canine monocytic ehrlichiosis is usually with antibiotics. Doxycycline is the most commonly used antibiotic and is given for at least 4 weeks. Early treatment can quickly relieve symptoms and control the infection.
In severe cases, especially in the chronic phase, supportive therapy may be required. This can include giving fluids for hydration, blood transfusions for severe anemia, and treating secondary infections.
It is important to continue treatment consistently and have the dog monitored regularly by a veterinarian to ensure the infection is completely eliminated and no relapses occur.
Prognosis and follow-up care
The prognosis for dogs with canine monocytic ehrlichiosis depends on the phase of the disease and how quickly treatment begins. Dogs treated in the acute phase usually have a good prognosis and recover fully.
In the chronic phase, the prognosis is more guarded because irreversible organ failure can occur. Early diagnosis and treatment are crucial to minimize the risk of long-term complications.
Some dogs may remain carriers of the bacteria despite treatment and are prone to relapses, especially if the immune system is weakened.
Prevention
Prevention of canine monocytic ehrlichiosis focuses mainly on tick control. Regular use of tick preventatives and checking 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 spending time in areas with high tick activity. Ticks should be removed as quickly as possible to prevent transmission of Ehrlichia bacteria.
Good general preventive care and regular veterinary check-ups can help monitor the dog’s health and respond early to possible infections. There is currently no vaccine against Ehrlichia canis, so tick control remains the most important prevention measure.
Outlook on current research
In canine monocytic ehrlichiosis (Ehrlichia canis), researchers are pursuing two paths: better detection and more targeted treatment. New blood tests combine antibody and PCR detection to identify early infections faster and distinguish relapses. In addition, biomarkers in blood and urine are being evaluated to show whether the bone marrow is damaged or whether the kidneys are affected. In therapy, researchers are investigating how long antibiotics are actually needed and which regimens best prevent relapses. In parallel, combinations of antibiotics and anti-inflammatory drugs are being tested to stabilize platelet counts more quickly. Another focus is protection against secondary damage such as kidney or ocular inflammation: standardized monitoring plans with blood counts, coagulation values, and urine tests help here. Vector control remains central. Studies compare collars, spot-ons, and tablets in endemic areas and analyze whether seasonal strategies make sense. Tick-borne co-infections (such as anaplasmas or babesia) are also specifically sought because they can worsen the course of disease. In the long term, vaccine approaches and immunomodulators are being explored to dampen excessive inflammatory responses without weakening defenses. The goal is an infection detected early, treated consistently, with a low risk of relapse and reliable protection of the organs.
Frequently Asked Questions (FAQs)
1. What is canine monocytic ehrlichiosis?
2. How can I recognize canine monocytic ehrlichiosis?
3. Is canine monocytic ehrlichiosis contagious between dogs?
4. How is canine monocytic ehrlichiosis diagnosed?
5. How is canine monocytic ehrlichiosis treated?
6. What is the prognosis for canine monocytic ehrlichiosis?
7. Are there relapses with canine monocytic ehrlichiosis?
8. What complications can occur with canine monocytic ehrlichiosis?
9. How can I prevent canine monocytic ehrlichiosis?
10. What should I monitor at home with canine monocytic ehrlichiosis?
Literature
- European Scientific Counsel Companion Animal Parasites. (2024). Control of vector-borne diseases in dogs and cats: ESCCAP guideline 5 (3rd ed.). ESCCAP. https://www.esccap.org/uploads/docs/32ir16g1_0775_ESCCAP_Guideline_GL5_20241203_1p.pdf
- Sainz, Á., Roura, X., Miró, G., Estrada-Peña, A., Kohn, B., Harrus, S., & Solano-Gallego, L. (2015). Guideline for veterinary practitioners on canine ehrlichiosis and anaplasmosis in Europe. Parasites & Vectors, 8, Article 75. https://doi.org/10.1186/s13071-015-0649-0
- Harrus, S., & Waner, T. (2011). Diagnosis of canine monocytotropic ehrlichiosis (Ehrlichia canis): An overview. The Veterinary Journal, 187(3), 292–296. https://doi.org/10.1016/j.tvjl.2010.02.001
- Mylonakis, M. E., Harrus, S., & Breitschwerdt, E. B. (2019). An update on the treatment of canine monocytic ehrlichiosis (Ehrlichia canis). The Veterinary Journal, 246, 45–53. https://doi.org/10.1016/j.tvjl.2019.01.015
- Aziz, M. U., Hussain, S., Song, B., Ghauri, H. N., Zeb, J., & Sparagano, O. (2022). Ehrlichiosis in dogs: A comprehensive review about the pathogen and its vectors with emphasis on South and East Asian countries. Veterinary Sciences, 10(1), Article 21. https://doi.org/10.3390/vetsci10010021
- Breitschwerdt, E. B., Hegarty, B. C., Hancock, S. I., & Finkelstein, J. L. (1998). Doxycycline hyclate treatment of experimental canine ehrlichiosis followed by challenge inoculation with two Ehrlichia canis strains. Antimicrobial Agents and Chemotherapy, 42(2), 362–368. https://doi.org/10.1128/AAC.42.2.362
- Eddlestone, S. M., Diniz, P. P. V. P., Neer, T. M., Gaunt, S. D., Corstvet, R. E., Cho, D., Hosgood, G., Hegarty, B. C., & Breitschwerdt, E. B. (2007). Doxycycline clearance of experimentally induced chronic Ehrlichia canis infection in dogs. Journal of Veterinary Internal Medicine, 21(6), 1237–1242. https://doi.org/10.1111/j.1939-1676.2007.tb01943.x
- Sumpavong, P., Srisawat, N., Foongladda, S., & Sukhumavasi, W. (2025). Visual detection of canine monocytic ehrlichiosis using PCR lateral flow biosensor targeting the Ehrlichia canis dsb gene. Animals, 15(5), Article 740. https://doi.org/10.3390/ani15050740
- European Scientific Counsel Companion Animal Parasites. (2024). Control of vector-borne diseases in dogs and cats: ESCCAP guideline 5 (3rd ed.). ESCCAP. https://www.esccap.org/uploads/docs/32ir16g1_0775_ESCCAP_Guideline_GL5_20241203_1p.pdf
- Sainz, Á., Roura, X., Miró, G., Estrada-Peña, A., Kohn, B., Harrus, S., & Solano-Gallego, L. (2015). Guideline for veterinary practitioners on canine ehrlichiosis and anaplasmosis in Europe. Parasites & Vectors, 8, Article 75. https://doi.org/10.1186/s13071-015-0649-0
- Harrus, S., & Waner, T. (2011). Diagnosis of canine monocytotropic ehrlichiosis (Ehrlichia canis): An overview. The Veterinary Journal, 187(3), 292–296. https://doi.org/10.1016/j.tvjl.2010.02.001
- Mylonakis, M. E., Harrus, S., & Breitschwerdt, E. B. (2019). An update on the treatment of canine monocytic ehrlichiosis (Ehrlichia canis). The Veterinary Journal, 246, 45–53. https://doi.org/10.1016/j.tvjl.2019.01.015
- Aziz, M. U., Hussain, S., Song, B., Ghauri, H. N., Zeb, J., & Sparagano, O. (2022). Ehrlichiosis in dogs: A comprehensive review about the pathogen and its vectors with emphasis on South and East Asian countries. Veterinary Sciences, 10(1), Article 21. https://doi.org/10.3390/vetsci10010021
- Breitschwerdt, E. B., Hegarty, B. C., Hancock, S. I., & Finkelstein, J. L. (1998). Doxycycline hyclate treatment of experimental canine ehrlichiosis followed by challenge inoculation with two Ehrlichia canis strains. Antimicrobial Agents and Chemotherapy, 42(2), 362–368. https://doi.org/10.1128/AAC.42.2.362
- Eddlestone, S. M., Diniz, P. P. V. P., Neer, T. M., Gaunt, S. D., Corstvet, R. E., Cho, D., Hosgood, G., Hegarty, B. C., & Breitschwerdt, E. B. (2007). Doxycycline clearance of experimentally induced chronic Ehrlichia canis infection in dogs. Journal of Veterinary Internal Medicine, 21(6), 1237–1242. https://doi.org/10.1111/j.1939-1676.2007.tb01943.x
- Sumpavong, P., Srisawat, N., Foongladda, S., & Sukhumavasi, W. (2025). Visual detection of canine monocytic ehrlichiosis using PCR lateral flow biosensor targeting the Ehrlichia canis dsb gene. Animals, 15(5), Article 740. https://doi.org/10.3390/ani15050740