Health & Diseases

Ehrlichiosis in Dogs: Symptoms, Diagnosis & Treatment

Ehrlichiosis is a tick-borne infectious disease caused by bacteria of the genus Ehrlichia. The most common form in dogs is Canine Monocytic Ehrlichiosis (CME), caused by Ehrlichia canis — primarily transmitted by the brown dog tick (Rhipicephalus sanguineus).

Ehrlichiosis in dogs: symptoms, diagnosis & treatment

What is ehrlichiosis in dogs?

Ehrlichiosis is a tick-borne infectious disease caused by bacteria of the genus Ehrlichia. The most common form in dogs is canine monocytic ehrlichiosis (CME), caused by Ehrlichia canis — transmitted mainly by the brown dog tick (Rhipicephalus sanguineus).

E. canis is not native to Germany, but it is a relevant finding in dogs that have been imported or brought in from the Mediterranean region, the Middle East, or Southeastern Europe. With increasing travel and import volumes, ehrlichiosis is also being diagnosed more frequently in Germany.

Background + scientific context

Neer et al. (2002, Journal of Veterinary Internal Medicine, PubMed 12144863) published the ACVIM consensus guidelines on ehrlichial diseases: the course of disease has three phases — acute (fever, lethargy, thrombocytopenia, 1–4 weeks after infection), subclinical (often without symptoms, months to years), and chronic (bone marrow insufficiency, severe thrombocytopenia, bleeding). The chronic phase has the poorest prognosis; early detection in the acute phase is crucial.

Harrus and Waner (2011, Veterinary Journal, PubMed 21237686) provided an overview of diagnostics for CME: serological tests (ELISA, IFA) are sensitive, but can be false-negative in the first 7–10 days after infection — antibody formation takes time. PCR is more sensitive in the early phase. Clinical presentation + serology results + blood count (thrombocytopenia is characteristic) form the diagnostic triad.

Diniz and Breitschwerdt (2012, Infectious Diseases of the Dog and Cat, Elsevier) described pathogenesis and treatment: doxycycline is the treatment of choice (25 mg/kg/day, at least 28 days). Clinical improvement is often seen after just 24–48 hours — starting treatment promptly when the disease is suspected (without waiting for serology confirmation) is justified in clinically affected dogs.

Vitomalia position

Ehrlichiosis is one of the diseases where travel history is crucial. A dog from the Mediterranean region with thrombocytopenia and fever should be considered to have ehrlichiosis until proven otherwise. If this screening is not offered as standard, diagnoses will be missed. When buying or adopting a dog from abroad: ehrlichiosis screening is recommended immediately after entry.

When does ehrlichiosis become relevant in dogs?

  • In dogs from or after travel to Mediterranean countries, Turkey, the Middle East
  • In cases of thrombocytopenia, fever, and lethargy of unknown cause
  • In cases of bleeding tendency (nosebleeds, petechiae) with no obvious cause
  • For travel screening: test together with leishmaniasis and Lyme disease
  • In imported dogs from Eastern Europe, Romania, Spain, Greece

Practical application

Clinical phases of CME:

Phase Duration Symptoms Treatment success
Acute 1–4 weeks Fever, lethargy, thrombocytopenia, lymphadenopathy Very good
Subclinical Months–years Often asymptomatic Good
Chronic Persistent Bone marrow failure, severe bleeding, edema Limited

Diagnostic algorithm: 1. History: origin, travel, tick exposure 2. Complete blood count: thrombocytopenia is characteristic 3. Serology (ELISA/IFA): positive from day 7–10 after infection 4. PCR in the early phase or when serology is uncertain 5. Start doxycycline treatment even when ehrlichiosis is suspected — waiting for diagnostic confirmation is not necessary when the clinical picture fits

Common mistakes & myths

  • “The dog was in Spain once, but that was 3 years ago.” Ehrlichiosis can remain subclinical for years and only become symptomatic in the chronic phase. The time elapsed since travel does not rule out CME.
  • “Thrombocytopenia is rare — I don’t need to test for Ehrlichia.” In dogs from the Mediterranean region, thrombocytopenia should be considered ehrlichiosis until proven otherwise — this differential diagnosis must be actively ruled out.
  • “Doxycycline does more harm than good.” Doxycycline for ehrlichiosis has few side effects and is highly effective. Delaying treatment, however, significantly increases the risk of a chronic course.

Scientific status 2026

Ehrlichiosis is increasing in Germany due to imported and traveling dogs. Rapid tests (SNAP tests) for Ehrlichia antibodies are widely available. PCR diagnostics improve sensitivity in the early phase. For prevention, tick protection with highly effective products (isoxazolines) reliably prevents transmission — important for dogs traveling in the Mediterranean region.

Frequently asked questions

How do I recognize ehrlichiosis in dogs?

Fever, lethargy, loss of appetite, tendency to bleed (nosebleeds, petechiae), and weight loss — especially in dogs with a history of travel to or origin from the Mediterranean region. Thrombocytopenia in the blood count is characteristic. A serological test and, if needed, PCR confirm the diagnosis.

How is ehrlichiosis treated in dogs?

Doxycycline (25 mg/kg/day, at least 28 days) is the treatment of choice. Clinical improvement often occurs within 24–48 hours. In cases of severe thrombocytopenia, a blood transfusion and supportive therapy may be needed. Starting treatment early helps prevent a chronic course.

Can ehrlichiosis be transmitted to humans?

Ehrlichia canis itself is not directly transmissible from dogs to humans — the route of transmission in humans is also the tick. Infected dogs do not pose a direct zoonotic risk, but tick control should be maintained.

Related terms

Sources & further reading

  1. Neer, T. M., Breitschwerdt, E. B., Greene, R. T., & Lappin, M. R. (2002). Consensus statement on ehrlichial disease of small animals from the Infectious Disease Study Group of the ACVIM. Journal of Veterinary Internal Medicine, 16(3), 309–315. https://pubmed.ncbi.nlm.nih.gov/12144863/

  2. Harrus, S., & Waner, T. (2011). Diagnosis of canine monocytotropic ehrlichiosis (Ehrlichia canis): an overview. Veterinary Journal, 187(3), 292–296. https://pubmed.ncbi.nlm.nih.gov/21237686/

  3. Diniz, P. P. V. P., & Breitschwerdt, E. B. (2012). Canine monocytotropic ehrlichiosis and neorickettsiosis. In C. E. Greene (Ed.), Infectious Diseases of the Dog and Cat (4th ed., pp. 227–238). Elsevier Saunders. ISBN 9781416070382.

Wissenschaftliche Einordnung

Neer et al. (2002, Journal of Veterinary Internal Medicine, PubMed 12144863) published the ACVIM Consensus Statement on Ehrlichial Diseases: The disease course has three phases—acute (fever, lethargy, thrombocytopenia, 1–4 weeks post-infection), subclinical (often asymptomatic, months to years), and chronic (bone marrow failure, severe thrombocytopenia, bleeding). The chronic phase has the worst prognosis; early detection in the acute phase is crucial.

Harrus and Waner (2011, Veterinary Journal, PubMed 21237686) described an overview of diagnostics for CME: Serological tests (ELISA, IFA) are sensitive but can be false-negative in the first 7–10 days post-infection—antibody production takes time. PCR is more sensitive in the early phase. Clinical picture + serology findings + blood count (thrombocytopenia is characteristic) constitute the diagnostic triad.

Diniz and Breitschwerdt (2012, Infectious Diseases of the Dog and Cat, Elsevier) described pathogenesis and therapy: Doxycycline is the drug of choice (25 mg/kg/day, for at least 28 days). Clinical improvement is often seen after 24–48 hours—rapid initiation of therapy in suspected cases (without waiting for serological confirmation) is justified in clinically affected dogs.