A case report of cutaneous vasculitis responsive to doxycycline with probably Rangeliosis etiology. Cutaneous vasculitis is a unusual disorder that affect dogs and its principal lesions are: purple, necrosis and extremity ulceration. More than half of the cases are of idiopathic etiology and, in the others, it is recognized some causes, such as vaccine reactions, drug reactions and lymphosarcoma. A patient, living in high risk area, 6 year Danish male dog showed a fever syndrome and bleeding from ear and mouth. The episode happened in hot season, in a period that the infestation by Ixodides is higher. In the clinical examination, we verified that there were bilateral hemorrhagic ulcers in the jugal mucosa, in auricle of inner ear and petechiae in auricle of ear. Laboratory analysis results: regenerative anemia, thrombocytopenia, regenerative leucocytes and ALT hepatic enzyme changed, without hemoglobinuria. As therapy, it was established doxycycline in 10mg/kg dose every twelve hours, VO, for 15 days. The treatment is reported to cure the patient. It is suggested Rangeliosis as the etiological responsible for the clinical situation of vasculitis, since the diagnosis of the disease can be made, considering the clinic signs and the response to the therapy, as well as the epidemiological data (time of the year, age, the place where the animal lives and the presence of ticks). Authors point out that cutaneous vasculitis was observed in dogs that have rickettsial (Rocky Mountain Spotted Fever), but there is no incidence of that disease in Rio Grande do Sul (RS). In a present study of twenty one cases of vasculitis, there was not any case of etiology caused by protozoa, although more than the half were idiopathic. We concluded that possibly the investigative resources were not enough to identify the cause this type of situation. Taking into considerations the epistemological data and the response to therapy, as well as the clinical signs, we suggest a Rangeliosis as vasculitis etiology, and the Doxicycline as a drug in the vasculitis treatment.