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Vetdle Archive

Archive Case #214: Canine Monocytic Ehrlichiosis

Dog veterinary case - Medium - October 3, 2026

Clinical Clues

  1. Rui, an adult dog recently brought from Portugal, is quiet, off his food and has an unexplained nosebleed.
  2. His history includes repeated tick exposure before travel; examination finds fever and pinpoint skin haemorrhages.
  3. Haematology shows marked thrombocytopenia, confirmed on a blood smear rather than explained by platelet clumping.
  4. Further examination finds enlarged lymph nodes, and blood chemistry shows increased globulins.
  5. Microscopy reveals a morula-like inclusion within a monocyte, increasing suspicion of an intracellular tick-borne infection.
  6. Species-specific PCR on a pretreatment blood sample detects Ehrlichia canis, supporting canine monocytic ehrlichiosis.

Diagnosis

Canine Monocytic Ehrlichiosis

Canine Monocytic Ehrlichiosis fits the travel history, bleeding and platelet loss, with pretreatment PCR identifying E. canis. Morulae are an insensitive finding and do not identify the species by themselves. Other tick-borne infections and immune-mediated thrombocytopenia can initially look similar. Remember: Travel history changes the differential list; identifying the organism helps distinguish similar tick-borne diseases.

Learning review

Review the case evidence

Use the paired clues to explain how the evidence in this dog case supports the provided diagnosis, Canine Monocytic Ehrlichiosis, then compare your reasoning with the case explanation.

Evidence checkpoints

Clues 1-2

  1. Clue 1: Rui, an adult dog recently brought from Portugal, is quiet, off his food and has an unexplained nosebleed.
  2. Clue 2: His history includes repeated tick exposure before travel; examination finds fever and pinpoint skin haemorrhages.

Clues 3-4

  1. Clue 3: Haematology shows marked thrombocytopenia, confirmed on a blood smear rather than explained by platelet clumping.
  2. Clue 4: Further examination finds enlarged lymph nodes, and blood chemistry shows increased globulins.

Clues 5-6

  1. Clue 5: Microscopy reveals a morula-like inclusion within a monocyte, increasing suspicion of an intracellular tick-borne infection.
  2. Clue 6: Species-specific PCR on a pretreatment blood sample detects Ehrlichia canis, supporting canine monocytic ehrlichiosis.

Self-review prompts

  1. After clues 1-2, what evidence from this dog case shaped your initial interpretation?
  2. When you compare clues 3-4 with clues 1-2, what changed in your reasoning about Canine Monocytic Ehrlichiosis?
  3. How do clues 5-6 align with the case explanation for Canine Monocytic Ehrlichiosis?

Educational Use

Vetdle archive cases are educational veterinary games for diagnostic reasoning practice. They do not provide veterinary advice, diagnosis, treatment, or professional medical guidance.