Ectoparasites can transmit pathogens, including bacteria such as Ehrlichia sp., which trigger infectious diseases in domestic animals. Little is known about the epidemiology of feline ehrlichiosis, although several studies have focused on elucidating the pathogenesis and transmission of this disease. This paper presents the first mutual infection by Ehrlichia sp. between a domestic cat and a Rhipicephalus sanguineus sensu lato (s.l.) tick removed from the animal. The cat and tick were tested by Polymerase Chain Reaction (PCR) to detect the dsb gene, and the analyzed sequences revealed samples 100% identical to E. canis. Based on this report, we discussed the importance of cats as E. canis reservoirs s and their position in the cycle of transmission between dogs and cats in Brazil.