Ehrlichia canis is a Gram-negative bacterium that acts as the causative agent of ehrlichiosis, a disease most commonly affecting canine species. It is primarily transmitted by the brown dog tick, Rhipicephalus sanguineus. Dogs, both domestic and wild, act as reservoir hosts for this pathogen.
Once inside the dog, the bacteria infect monocytes and are capable of spreading throughout the lymphatic system, including the spleen and liver. Animals infected with E. canis may experience a combination of signs, including fever, lethargy, weight loss, lymphadenopathy, edema of the appendages, discharge from nose and eyes, and seizures. If the infection is not treated, the disease can take on a chronic form, where bone marrow will fail to develop along with anemia, making the dog more susceptible to other infections.