Ehrlichiosis is a tick-borne disease that is caused by a rickettsial organism, a type of bacteria that can infect dogs, humans, and, rarely, cats. Brown dog ticks are responsible for the transmission of Ehrlichia canis, the most common cause of ehrlichiosis in North America. Transmission generally occurs within several hours of tick attachment, with clinical signs appearing 1 – 3 weeks later.


Ehrlichiosis is generally broken down into three different stages.

Acute Stage: 1 – 3 weeks after exposure

Subacute Phase: Months to years after exposure

Chronic Phase:

Though much less common, infected dogs can also exhibit eye and nervous system symptoms. The severity of the disease likely depends upon the disease strain, immune compromise, and co-infection with other tick-borne diseases. German shepherds also appear to be predisposed to developing more severe, chronic forms of ehrlichiosis.


Diagnosis is generally based on clinical signs, a history of tick exposure, and positive antibody testing. Additional diagnostics include:


Treatment with tetracycline antibiotics, such as doxycycline, for 4 weeks is the recommended treatment course for ehrlichiosis. When caught early in the acute phase, treatment generally carries a good prognosis.