Canine monocytic ehrlichiosis (CME), previously known as canine rickettsiosis, canine hemorrhagic fever, tracker dog disease, canine tick typhus, Nairobi bleeding disorder, and tropical canine pancytopenia, is a tick-borne disease caused by rickettsia Ehrlichia canis, a small Gram-negative, coccoid bacterium. Ehrlichia canis is transmitted by the brown dog-tick Rhipicephalus sanguineus. The disease has been reported to occur in Asia, Africa, Europe, and America. To date, no effective vaccine has been developed and tick control remains the most effective preventive measure.
The course of ehrlichiosis can be divided into three phases: acute, subclinical, and chronic, each one being characterized by specific signs. Signs of the acute phase may include depression, lethargy, fever, enlarged lymph nodes, and occasional bleeding under skin and in the internal eye that may result in retinal detachment and blindness. Other clinical signs may include vomiting, clear or pus-filled discharge form the eyes and nose, lameness, loss of movement coordination, and difficulty breathing.