ABSTRACT. Oliveira H.H., Lima J.C., Fernandes A.B., Zangaro R.A. & Moreira L.H. [Ozonated oil uses in topical treatment of tick infestation in dog - Case report.] Uso de óleo ozonizado no tratamento tópico de infestação por carrapato em cão - Relato de caso. Revista Brasileira de Medicina Veterinária, 36(4):405-408, 2014. Instituto de Engenharia Biomédica, Unicastelo, Parque Tecnológico de São José dos Campos, Estrada Doutor Altino Bondesan, 500 Distrito Eugênio de Melo, São José dos Campos, SP 12247- 016, Brasil. E-mail: lhsil@uol.com.br Rhipicephalus sanguineus is a common tick in dogs. Mild skin lesions, irritation and even anemia can be caused by high infestations. A case report describes a treatment where ozonated oil was applied in dogs with tick infestation. A significant improvement of erythemas in the ears and abdomen was observed, as well as in skin lesions. This result confirms the ozone efficiency in bactericidal effect and the improve of healing process therefore that topical application of ozonated oil in dog infested by R. sanguineus has effect acaricide.