Ehrlichiosis and Anaplasmosis

Ehrlichiosis and anaplasmosis are tick-borne diseases caused by a group of gram-negative intracellular bacteria belonging to the family Anaplasmataceae, order Rickettsiales. These organisms are capable of causing an array of clinical signs and even death in dogs. This chapter focuses on infection in dogs. For dogs, Ehrlichia canis is the most pathogenic organism, targeting monocytes and rarely lymphocytes. Dogs infected with Ehrlichia canis may develop polyclonal or monoclonal hypergammaglobulinemia. The classic presentation in dogs is characterized by depression, lethargy, mild weight loss, and anorexia. Diagnosis is generally based on clinical and hematologic abnormalities, response to therapy and presence of specific antibodies against Ehrlichia and Anaplasma spp. Doxycycline remains the treatment of choice for ehrlichiosis and anaplasmosis. Acute ehrlichiosis and anaplasmosis have very good prognosis if antibiotic therapy is initiated immediately.