Ehrlichia canis

Canine monocytic ehrlichiosis

• Generalised disease of dogs in tropical and subtropical regions
• Caused by Ehrlichia canis
• The brown tick, Rhipicephalus sanguineus, is the main vector
• Dogs may carry the organism for 2 years after resolution of clinical signs

• Clinical signs
  • Incubation period of 3 weeks
  • Acute, subclinical or chronic phases
  • Acute phase: fever, thrombocytopenia, leukopenia and anaemia
  • Subclinical phase: low blood cell numbers but minimal clinical signs; can progress to a severe disease, tropical canine pancytopenia
  • Chronic phase: bone marrow depression, haemorrhages, neurological disease, peripheral oedema, emaciation and hypotensive shock

• Diagnosis
  • E. canis morulae present in mononuclear cells in Giemsa-stained blood smears
  • Rising antibody titre detected by indirect immunofluorescence
  • Culture in canine macrophages

• Treatment and control
  • Doxycycline for 10 days
  • Fluid therapy or blood transfusion
  • Prophylactic tetracyclines