background : the aims of this study were to determine the seroprevalence of canine ehrlichiosis and risk factors of this disease in companion dogs’ population of mashhad, north east of iran. canine monocytic ehrlichiosis (cme) is a zoonotic disease transmitted by ticks, rhipicephalus sanguineus, and caused by an obligate intracellular bacterium, ehrlichia canis. methods : during september 2009 ...