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Hematologic · Dogs

Canine Monocytic Ehrlichiosis

Canine Monocytic Ehrlichiosis (CME, Tropical canine pancytopenia, Tracker dog disease) is a hematologic condition of dogs. Key signs are fever, lethargy, anorexia, weight loss and lymphadenopathy and splenomegaly; diagnosis rests on CBC: thrombocytopenia, non-regenerative anaemia, pancytopenia in chronic phase and Serum biochemistry: hyperglobulinaemia, hypoalbuminaemia. Excellent in acute phase if treated promptly.

At a glance

Species
Dogs
Body system
Hematologic
Also known as
CME, Tropical canine pancytopenia, Tracker dog disease

Key clinical signs

  • Fever
  • Lethargy, anorexia, weight loss
  • Lymphadenopathy and splenomegaly
  • Bleeding diathesis: epistaxis, petechiae, melena
  • Pale mucous membranes (anaemia)

Other signs

  • Ocular: anterior uveitis, retinal haemorrhage
  • Polyarthritis
  • CNS signs in chronic phase
  • Edema of limbs

Differential diagnoses

  • Babesiosis
  • Leishmaniasis
  • Rocky Mountain Spotted Fever
  • Anaplasmosis (A. phagocytophilum)
  • Immune-mediated thrombocytopenia
  • Lymphoma
  • Multiple myeloma (chronic phase hyperglobulinaemia)

Diagnosis

  • CBC: thrombocytopenia (most consistent), non-regenerative anaemia, pancytopenia in chronic phase
  • Serum biochemistry: hyperglobulinaemia (often monoclonal in chronic phase), hypoalbuminaemia
  • IFA or ELISA antibody titres for E. canis (commercial 4DX SNAP)
  • PCR for E. canis DNA (most useful in acute phase)
  • Blood smear: morulae in monocytes (low sensitivity)

Treatment outline

Doxycycline 10 mg/kg PO q24h for 28 days is the treatment of choice (Plumb's p. 450). Corticosteroids may be added short-term in cases of severe immune-mediated thrombocytopenia. Blood transfusion if severe anaemia or active bleeding. Tick prevention. Prognosis poorer in chronic pancytopenic phase.

An outline, not a prescription. Check each drug’s dose for the species, the patient and the product in the drug calculator before use.

Prognosis

Excellent in acute phase if treated promptly. Guarded-to-poor in chronic pancytopenic phase due to bone-marrow failure.

Frequently asked questions

What are the signs of canine monocytic ehrlichiosis in dogs?

Fever, lethargy, anorexia, weight loss, lymphadenopathy and splenomegaly, bleeding diathesis: epistaxis, petechiae, melena and pale mucous membranes (anaemia). Less specific signs include ocular: anterior uveitis, retinal haemorrhage, polyarthritis and cns signs in chronic phase.

How is canine monocytic ehrlichiosis diagnosed?

CBC: thrombocytopenia (most consistent), non-regenerative anaemia, pancytopenia in chronic phase, Serum biochemistry: hyperglobulinaemia (often monoclonal in chronic phase), hypoalbuminaemia, IFA or ELISA antibody titres for E. canis (commercial 4DX SNAP), PCR for E. canis DNA (most useful in acute phase) and Blood smear: morulae in monocytes (low sensitivity). Differentials to rule out include babesiosis, leishmaniasis, rocky mountain spotted fever and anaplasmosis (a. phagocytophilum).

How is canine monocytic ehrlichiosis treated?

Doxycycline 10 mg/kg PO q24h for 28 days is the treatment of choice (Plumb's p. 450). Corticosteroids may be added short-term in cases of severe immune-mediated thrombocytopenia. Blood transfusion if severe anaemia or active bleeding. Tick prevention. Prognosis poorer in chronic pancytopenic phase.

What is the prognosis for canine monocytic ehrlichiosis?

Excellent in acute phase if treated promptly. Guarded-to-poor in chronic pancytopenic phase due to bone-marrow failure.

Sources

  • Merck Veterinary Manual, 11th edition

Last reviewed · VetMasterJi