Granulocytic ehrlichiosis and meningitis in a dog.

A 4-year-old male mixed-breed dog from the Sierra Nevada mountains in California was referred because of epistaxis and signs of cervical pain. Dermacentor variabilis ticks were found on the dog at the time of physical examination. Clinicopathologic abnormalities included nonregenerative anemia, thrombocytopenia, and rare intracytoplasmic morulae within circulating neutrophils. Abnormalities of the CSF included pleocytosis and intracytoplasmic morulae in approximately 9% of neutrophils. Serum antibody titers for Ehrlichia canis (40,960) and Rickettsia rickettsii (5,120) were high, and titer for E equi (40) was moderate. Treatment included administration of tetracycline, chloramphenicol, doxycycline, and prednisone. The dog had several relapses, but long-term remission was eventually achieved. Granulocytic ehrlichiosis has previously been associated with anemia, thrombocytopenia, and polyarthritis in dogs. This case suggests that granulocytic ehrlichiosis may be associated with meningitis and that the organisms that cause granulocytic ehrlichiosis may have the same vector as do the spotted fever-group rickettsiae.