Ehrlichiosis in Dogs: Symptoms, Diagnosis, and 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 primarily by the brown dog tick (Rhipicephalus sanguineus).

E. canis is not native to Germany, but it is a significant finding in dogs that have been imported from or brought back from the Mediterranean region, the Middle East, or Southeast Europe. As travel and import volumes increase, 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 ehrlichiosis: The disease course has three phases—acute (fever, lethargy, thrombocytopenia, 1–4 weeks after infection), subclinical (often asymptomatic, months to years), and chronic (bone marrow failure, severe thrombocytopenia, hemorrhage). The chronic phase has the poorest prognosis; early detection during the acute phase is crucial.

Harrus and Waner (2011, Veterinary Journal, PubMed 21237686) described an overview of diagnostic methods for CME: Serological tests (ELISA, IFA) are sensitive but may yield false-negative results in the first 7–10 days after infection—it takes time for antibodies to develop. PCR is more sensitive in the early phase. Clinical presentation + serological findings + blood count (thrombocytopenia is characteristic) constitute the diagnostic triad.

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

Vitomalia-Position

Ehrlichiosis is one of the diseases for which travel history is crucial. A dog from the Mediterranean region with thrombocytopenia and fever is presumed to have ehrlichiosis until proven otherwise. Clinics that do not routinely offer this screening will miss diagnoses. When purchasing or adopting a dog from abroad: Ehrlichiosis screening is recommended immediately upon arrival.

When does ehrlichiosis become a concern in dogs?

• For dogs coming from or returning from trips to Mediterranean countries, Turkey, or the Middle East
• In cases of thrombocytopenia, fever, and lethargy of unknown cause
• If you experience a tendency to bleed (nosebleeds, petechiae) without any obvious cause
• For travel screening: test for leishmaniasis and Lyme disease at the same time
• For dogs imported from Eastern Europe, Romania, Spain, and Greece

Practical application

Clinical phases of CME:

Diagnostic algorithm: 1. Medical history: Background, travel history, exposure to ticks 2. Complete blood count: Characteristic thrombocytopenia 3. Serology (ELISA/IFA): positive starting on days 7–10 after infection 4. PCR in the early stages or when serology results are inconclusive 5. Initiate doxycycline treatment even in cases of suspected infection — it is not necessary to wait for confirmation of the diagnosis based on clinical presentation

Common Mistakes & Myths

• “The dog was in Spain once, three years ago.” Ehrlichiosis can remain subclinical for years and only become symptomatic in the chronic phase. The time that has elapsed since the trip does not rule out CME.
• “Thrombocytopenia is rare—I don’t need to test for ehrlichiosis.” Until proven otherwise, thrombocytopenia in Mediterranean dogs is ehrlichiosis—this diagnosis must be actively ruled out.
• “Doxycycline does more harm than good.” Doxycycline is highly effective and has few side effects when used to treat ehrlichiosis. Delaying treatment, on the other hand, significantly increases the risk of the disease becoming chronic.

Current State of Research (2026)

Ehrlichiosis is on the rise in Germany due to imported dogs and dogs traveling abroad. Rapid tests (SNAP tests) for Ehrlichia antibodies are widely available. PCR testing improves sensitivity in the early stages. Prevention: Tick protection using highly effective products (isoxazolines) reliably prevents transmission—this is important for dogs traveling to the Mediterranean region.

Frequently Asked Questions

How can I tell if my dog has ehrlichiosis?

Fever, lethargy, loss of appetite, tendency to bleed (nosebleeds, petechiae), and weight loss—especially in dogs with a history of travel to the Mediterranean. Thrombocytopenia on a blood count is characteristic. Serological testing and, if necessary, PCR confirm the diagnosis.

How is ehrlichiosis treated in dogs?

Doxycycline (25 mg/kg/day, for at least 28 days) is the drug of choice. Clinical improvement is often seen within 24–48 hours. In cases of severe thrombocytopenia, blood transfusions and supportive care may be necessary. Early initiation of treatment prevents the condition from becoming chronic.

Is ehrlichiosis transmissible to humans?

Ehrlichia canis itself cannot be transmitted directly from dogs to humans—the route of transmission in humans is also via ticks. Infected dogs do not pose a direct zoonotic risk, but should be monitored for ticks.

Related terms

• Ticks on Dogs
• Leishmaniasis in Dogs
• Lyme disease in dogs
• Complete blood count in dogs
• Traveling with Your Dog

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.