Abstract: Ehrlichia canis is an important zoonotic infectious pathogen and causes monocytic ehrlichiasis in canine.In order to diagnose a case of pet dog clinically characterized by fever,depression and paleness of mucosa,the blood routine test,blood biochemical test,real-time fluorescent quantitative PCR,and Ehrlichia canis antibody test were carried out.This case was confirmly diagnosed as Ehrlichia canis infection.The doxycycline hydrochloride was used to treat the dog and good curative effect was obtained.